Compare regions, not four loose numbers

`PixelRegion` derives `PartialEq`, `Clone` and `Copy`, so `assert_corners!`
compares one against another instead of flattening both to a tuple whose
order there was nothing to check. A failure now prints two regions.

Cargo.lock

@@ -234,18 +234,18 @@ dependencies = [
 
 [[package]]
 name = "bit-set"
-version = "0.8.0"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "08807e080ed7f9d5433fa9b275196cfc35414f66a0c79d864dc51a0d825231a3"
+checksum = "09ec2f926cc3060f09db9ebc5b52823d85268d24bb917e472c0c4bea35780a7d"
 dependencies = [
  "bit-vec",
 ]
 
 [[package]]
 name = "bit-vec"
-version = "0.8.0"
+version = "0.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e764a1d40d510daf35e07be9eb06e75770908c27d411ee6c92109c9840eaaf7"
+checksum = "b71798fca2c1fe1086445a7258a4bc81e6e49dcd24c8d0dd9a1e57395b603f51"
 
 [[package]]
 name = "bit_field"
@@ -274,12 +274,6 @@ dependencies = [
  "core2",
 ]
 
-[[package]]
-name = "block"
-version = "0.1.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0d8c1fef690941d3e7788d328517591fecc684c084084702d6ff1641e993699a"
-
 [[package]]
 name = "block2"
 version = "0.5.1"
@@ -289,6 +283,15 @@ dependencies = [
  "objc2 0.5.2",
 ]
 
+[[package]]
+name = "block2"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cdeb9d870516001442e364c5220d3574d2da8dc765554b4a617230d33fa58ef5"
+dependencies = [
+ "objc2 0.6.4",
+]
+
 [[package]]
 name = "built"
 version = "0.8.0"
@@ -391,9 +394,9 @@ checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
 [[package]]
 name = "cfg_aliases"
-version = "0.2.1"
+version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
+checksum = "f079e83a288787bcd14a6aea84cee5c87a67c5a3e660c30f557a3d24761b3527"
 
 [[package]]
 name = "clipboard-win"
@@ -406,9 +409,9 @@ dependencies = [
 
 [[package]]
 name = "codespan-reporting"
-version = "0.12.0"
+version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fe6d2e5af09e8c8ad56c969f2157a3d4238cebc7c55f0a517728c38f7b200f81"
+checksum = "af491d569909a7e4dee0ad7db7f5341fef5c614d5b8ec8cf765732aba3cff681"
 dependencies = [
  "serde",
  "termcolor",
@@ -450,16 +453,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "core-foundation"
-version = "0.10.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b2a6cd9ae233e7f62ba4e9353e81a88df7fc8a5987b8d445b4d90c879bd156f6"
-dependencies = [
- "core-foundation-sys",
- "libc",
-]
-
 [[package]]
 name = "core-foundation-sys"
 version = "0.8.7"
@@ -473,8 +466,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c07782be35f9e1140080c6b96f0d44b739e2278479f64e02fdab4e32dfd8b081"
 dependencies = [
  "bitflags 1.3.2",
- "core-foundation 0.9.4",
+ "core-foundation",
- "core-graphics-types 0.1.3",
+ "core-graphics-types",
  "foreign-types",
  "libc",
 ]
@@ -486,18 +479,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "45390e6114f68f718cc7a830514a96f903cccd70d02a8f6d9f643ac4ba45afaf"
 dependencies = [
  "bitflags 1.3.2",
- "core-foundation 0.9.4",
+ "core-foundation",
- "libc",
-]
-
-[[package]]
-name = "core-graphics-types"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3d44a101f213f6c4cdc1853d4b78aef6db6bdfa3468798cc1d9912f4735013eb"
-dependencies = [
- "bitflags 2.10.0",
- "core-foundation 0.10.1",
  "libc",
 ]
 
@@ -739,15 +721,6 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "77ce24cb58228fbb8aa041425bb1050850ac19177686ea6e0f41a70416f56fdb"
 
-[[package]]
-name = "font-types"
-version = "0.10.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "39a654f404bbcbd48ea58c617c2993ee91d1cb63727a37bf2323a4edeed1b8c5"
-dependencies = [
- "bytemuck",
-]
-
 [[package]]
 name = "font-types"
 version = "0.12.4"
@@ -771,7 +744,7 @@ dependencies = [
  "objc2-core-text",
  "objc2-foundation 0.3.2",
  "parlance",
- "read-fonts 0.41.0",
+ "read-fonts",
  "roxmltree",
  "smallvec",
  "windows",
@@ -806,6 +779,30 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "aa9a19cbb55df58761df49b23516a86d432839add4af60fc256da840f66ed35b"
 
+[[package]]
+name = "futures-core"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92d699e522242e69e3003b94ecc1f960f3a5e015aa7c5d7486e65ad01dd94f5e"
+
+[[package]]
+name = "futures-task"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd417de3d1d015fc3bfd2b1ea46dfc7bab72ef86f1cc7cc9c78e728b34a6d1fd"
+
+[[package]]
+name = "futures-util"
+version = "0.3.34"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d50a92467f8ba5dd6e3ee5d4bd04d73ab2e4e1c44474a0674821dfce14b79bc"
+dependencies = [
+ "futures-core",
+ "futures-task",
+ "pin-project-lite",
+ "slab",
+]
+
 [[package]]
 name = "fxhash"
 version = "0.2.1"
@@ -860,9 +857,9 @@ dependencies = [
 
 [[package]]
 name = "glow"
-version = "0.16.0"
+version = "0.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c5e5ea60d70410161c8bf5da3fdfeaa1c72ed2c15f8bbb9d19fe3a4fad085f08"
+checksum = "29038e1c483364cc6bb3cf78feee1816002e127c331a1eec55a4d202b9e1adb5"
 dependencies = [
  "js-sys",
  "slotmap",
@@ -893,26 +890,6 @@ dependencies = [
  "windows",
 ]
 
-[[package]]
-name = "gpu-descriptor"
-version = "0.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b89c83349105e3732062a895becfc71a8f921bb71ecbbdd8ff99263e3b53a0ca"
-dependencies = [
- "bitflags 2.10.0",
- "gpu-descriptor-types",
- "hashbrown 0.15.5",
-]
-
-[[package]]
-name = "gpu-descriptor-types"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fdf242682df893b86f33a73828fb09ca4b2d3bb6cc95249707fc684d27484b91"
-dependencies = [
- "bitflags 2.10.0",
-]
-
 [[package]]
 name = "half"
 version = "2.7.1"
@@ -933,7 +910,7 @@ checksum = "c03d949a14aa089bbb282f7dd76a498a7f684428e4257202efc119ec010376f9"
 dependencies = [
  "bitflags 2.10.0",
  "bytemuck",
- "read-fonts 0.41.0",
+ "read-fonts",
  "smallvec",
 ]
 
@@ -972,12 +949,6 @@ version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fc0fef456e4baa96da950455cd02c081ca953b141298e41db3fc7e36b1da849c"
 
-[[package]]
-name = "hexf-parse"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dfa686283ad6dd069f105e5ab091b04c62850d3e4cf5d67debad1933f55023df"
-
 [[package]]
 name = "icu_collections"
 version = "2.3.0"
@@ -1108,9 +1079,9 @@ checksum = "ae293c039020f9ec10710af98d29ce6aa2051486638b49c9a6409f3b4a9e98ad"
 
 [[package]]
 name = "image"
-version = "0.25.9"
+version = "0.25.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6506c6c10786659413faa717ceebcb8f70731c0a60cbae39795fdf114519c1a"
+checksum = "85ab80394333c02fe689eaf900ab500fbd0c2213da414687ebf995a65d5a6104"
 dependencies = [
  "bytemuck",
  "byteorder-lite",
@@ -1126,8 +1097,8 @@ dependencies = [
  "rayon",
  "rgb",
  "tiff",
- "zune-core 0.5.0",
+ "zune-core",
- "zune-jpeg 0.5.8",
+ "zune-jpeg",
 ]
 
 [[package]]
@@ -1247,11 +1218,12 @@ dependencies = [
 
 [[package]]
 name = "js-sys"
-version = "0.3.83"
+version = "0.3.105"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "464a3709c7f55f1f721e5389aa6ea4e3bc6aba669353300af094b29ffbdde1d8"
+checksum = "ce57d20d1ea864ce2ac172ab472d409214f4fd359f0b2a2775abdf522e2af99e"
 dependencies = [
- "once_cell",
+ "cfg-if",
+ "futures-util",
  "wasm-bindgen",
 ]
 
@@ -1280,9 +1252,9 @@ checksum = "7a79a3332a6609480d7d0c9eab957bca6b455b91bb84e66d19f5ff66294b85b8"
 
 [[package]]
 name = "libc"
-version = "0.2.179"
+version = "0.2.189"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c5a2d376baa530d1238d133232d15e239abad80d05838b4b59354e5268af431f"
+checksum = "3eaf3ede3fee6db1a4c2ee091bf8a8b4dccdc6d17f656fb07896ee72867612f2"
 
 [[package]]
 name = "libfuzzer-sys"
@@ -1375,15 +1347,6 @@ dependencies = [
  "imgref",
 ]
 
-[[package]]
-name = "malloc_buf"
-version = "0.0.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "62bb907fe88d54d8d9ce32a3cceab4218ed2f6b7d35617cafe9adf84e43919cb"
-dependencies = [
- "libc",
-]
-
 [[package]]
 name = "maybe-rayon"
 version = "0.1.1"
@@ -1409,21 +1372,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "metal"
-version = "0.33.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7047791b5bc903b8cd963014b355f71dc9864a9a0b727057676c1dcae5cbc15"
-dependencies = [
- "bitflags 2.10.0",
- "block",
- "core-graphics-types 0.2.0",
- "foreign-types",
- "log",
- "objc",
- "paste",
-]
-
 [[package]]
 name = "miniz_oxide"
 version = "0.8.9"
@@ -1436,9 +1384,9 @@ dependencies = [
 
 [[package]]
 name = "moxcms"
-version = "0.7.11"
+version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac9557c559cd6fc9867e122e20d2cbefc9ca29d80d027a8e39310920ed2f0a97"
+checksum = "bb85c154ba489f01b25c0d36ae69a87e4a1c73a72631fc6c0eb6dde34a73e44b"
 dependencies = [
  "num-traits",
  "pxfm",
@@ -1446,9 +1394,9 @@ dependencies = [
 
 [[package]]
 name = "naga"
-version = "28.0.0"
+version = "30.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "618f667225063219ddfc61251087db8a9aec3c3f0950c916b614e403486f1135"
+checksum = "a616d2fb8c89516ac2723a581f69d6c18576046bed761bd6b305e5618e6ae130"
 dependencies = [
  "arrayvec",
  "bit-set",
@@ -1457,11 +1405,11 @@ dependencies = [
  "cfg_aliases",
  "codespan-reporting",
  "half",
- "hashbrown 0.16.1",
+ "hashbrown 0.17.1",
- "hexf-parse",
  "indexmap",
  "libm",
  "log",
+ "naga-types",
  "num-traits",
  "once_cell",
  "rustc-hash",
@@ -1470,6 +1418,18 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "naga-types"
+version = "30.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "590afbf58a6f4f62873cd5cff4468061844bafa1cdf399cc954537c22d768d49"
+dependencies = [
+ "hashbrown 0.17.1",
+ "indexmap",
+ "rustc-hash",
+ "thiserror 2.0.17",
+]
+
 [[package]]
 name = "ndk"
 version = "0.9.0"
@@ -1594,15 +1554,6 @@ dependencies = [
  "syn 2.0.113",
 ]
 
-[[package]]
-name = "objc"
-version = "0.2.7"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "915b1b472bc21c53464d6c8461c9d3af805ba1ef837e1cac254428f4a77177b1"
-dependencies = [
- "malloc_buf",
-]
-
 [[package]]
 name = "objc-sys"
 version = "0.3.5"
@@ -1635,13 +1586,13 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e4e89ad9e3d7d297152b17d39ed92cd50ca8063a89a9fa569046d41568891eff"
 dependencies = [
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "libc",
  "objc2 0.5.2",
  "objc2-core-data",
  "objc2-core-image",
  "objc2-foundation 0.2.2",
- "objc2-quartz-core",
+ "objc2-quartz-core 0.2.2",
 ]
 
 [[package]]
@@ -1663,7 +1614,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "74dd3b56391c7a0596a295029734d3c1c5e7e510a4cb30245f8221ccea96b009"
 dependencies = [
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-core-location",
  "objc2-foundation 0.2.2",
@@ -1675,7 +1626,7 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a5ff520e9c33812fd374d8deecef01d4a840e7b41862d849513de77e44aa4889"
 dependencies = [
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-foundation 0.2.2",
 ]
@@ -1687,7 +1638,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "617fbf49e071c178c0b24c080767db52958f716d9eabdf0890523aeae54773ef"
 dependencies = [
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-foundation 0.2.2",
 ]
@@ -1722,10 +1673,10 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "55260963a527c99f1819c4f8e3b47fe04f9650694ef348ffd2227e8196d34c80"
 dependencies = [
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-foundation 0.2.2",
- "objc2-metal",
+ "objc2-metal 0.2.2",
 ]
 
 [[package]]
@@ -1734,7 +1685,7 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "000cfee34e683244f284252ee206a27953279d370e309649dc3ee317b37e5781"
 dependencies = [
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-contacts",
  "objc2-foundation 0.2.2",
@@ -1763,7 +1714,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0ee638a5da3799329310ad4cfa62fbf045d5f56e3ef5ba4149e7452dcf89d5a8"
 dependencies = [
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "dispatch",
  "libc",
  "objc2 0.5.2",
@@ -1797,7 +1748,7 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a1a1ae721c5e35be65f01a03b6d2ac13a54cb4fa70d8a5da293d7b0020261398"
 dependencies = [
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-app-kit 0.2.2",
  "objc2-foundation 0.2.2",
@@ -1810,11 +1761,23 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dd0cba1276f6023976a406a14ffa85e1fdd19df6b0f737b063b95f6c8c7aadd6"
 dependencies = [
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-foundation 0.2.2",
 ]
 
+[[package]]
+name = "objc2-metal"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a0125f776a10d00af4152d74616409f0d4a2053a6f57fa5b7d6aa2854ac04794"
+dependencies = [
+ "bitflags 2.10.0",
+ "block2 0.6.2",
+ "objc2 0.6.4",
+ "objc2-foundation 0.3.2",
+]
+
 [[package]]
 name = "objc2-quartz-core"
 version = "0.2.2"
@@ -1822,10 +1785,24 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e42bee7bff906b14b167da2bac5efe6b6a07e6f7c0a21a7308d40c960242dc7a"
 dependencies = [
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-foundation 0.2.2",
- "objc2-metal",
+ "objc2-metal 0.2.2",
+]
+
+[[package]]
+name = "objc2-quartz-core"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "96c1358452b371bf9f104e21ec536d37a650eb10f7ee379fff67d2e08d537f1f"
+dependencies = [
+ "bitflags 2.10.0",
+ "objc2 0.6.4",
+ "objc2-core-foundation",
+ "objc2-core-graphics",
+ "objc2-foundation 0.3.2",
+ "objc2-metal 0.3.2",
 ]
 
 [[package]]
@@ -1845,7 +1822,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b8bb46798b20cd6b91cbd113524c490f1686f4c4e8f49502431415f3512e2b6f"
 dependencies = [
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-cloud-kit",
  "objc2-core-data",
@@ -1853,7 +1830,7 @@ dependencies = [
  "objc2-core-location",
  "objc2-foundation 0.2.2",
  "objc2-link-presentation",
- "objc2-quartz-core",
+ "objc2-quartz-core 0.2.2",
  "objc2-symbols",
  "objc2-uniform-type-identifiers",
  "objc2-user-notifications",
@@ -1865,7 +1842,7 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "44fa5f9748dbfe1ca6c0b79ad20725a11eca7c2218bceb4b005cb1be26273bfe"
 dependencies = [
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-foundation 0.2.2",
 ]
@@ -1877,7 +1854,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "76cfcbf642358e8689af64cee815d139339f3ed8ad05103ed5eaf73db8d84cb3"
 dependencies = [
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "objc2 0.5.2",
  "objc2-core-location",
  "objc2-foundation 0.2.2",
@@ -1971,7 +1948,7 @@ dependencies = [
  "linebender_resource_handle",
  "parlance",
  "parley_data",
- "skrifa 0.44.0",
+ "skrifa",
 ]
 
 [[package]]
@@ -2275,9 +2252,9 @@ dependencies = [
 
 [[package]]
 name = "ravif"
-version = "0.12.0"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ef69c1990ceef18a116855938e74793a5f7496ee907562bd0857b6ac734ab285"
+checksum = "e52310197d971b0f5be7fe6b57530dcd27beb35c1b013f29d66c1ad73fbbcc45"
 dependencies = [
  "avif-serialize",
  "imgref",
@@ -2294,6 +2271,18 @@ version = "0.6.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "20675572f6f24e9e76ef639bc5552774ed45f1c30e2951e1e99c59888861c539"
 
+[[package]]
+name = "raw-window-metal"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40d213455a5f1dc59214213c7330e074ddf8114c9a42411eb890c767357ce135"
+dependencies = [
+ "objc2 0.6.4",
+ "objc2-core-foundation",
+ "objc2-foundation 0.3.2",
+ "objc2-quartz-core 0.3.2",
+]
+
 [[package]]
 name = "rayon"
 version = "1.11.0"
@@ -2314,16 +2303,6 @@ dependencies = [
  "crossbeam-utils",
 ]
 
-[[package]]
-name = "read-fonts"
-version = "0.36.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5eaa2941a4c05443ee3a7b26ab076a553c343ad5995230cc2b1d3e993bdc6345"
-dependencies = [
- "bytemuck",
- "font-types 0.10.1",
-]
-
 [[package]]
 name = "read-fonts"
 version = "0.41.0"
@@ -2331,7 +2310,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "046a7d674daf459825b32f5062056d6882db0d2f5a479fbd76ccfc870ac18709"
 dependencies = [
  "bytemuck",
- "font-types 0.12.4",
+ "font-types",
  "once_cell",
 ]
 
@@ -2506,16 +2485,6 @@ dependencies = [
  "quote",
 ]
 
-[[package]]
-name = "skrifa"
-version = "0.39.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c9eb0b904a04d09bd68c65d946617b8ff733009999050f3b851c32fb3cfb60e"
-dependencies = [
- "bytemuck",
- "read-fonts 0.36.0",
-]
-
 [[package]]
 name = "skrifa"
 version = "0.44.0"
@@ -2523,7 +2492,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "819ab7d62b1d3e72d9d9dea5650bac30424f9111364bb94928dbf5ecad1baa68"
 dependencies = [
  "bytemuck",
- "read-fonts 0.41.0",
+ "read-fonts",
 ]
 
 [[package]]
@@ -2583,9 +2552,9 @@ dependencies = [
 
 [[package]]
 name = "spirv"
-version = "0.3.0+sdk-1.3.268.0"
+version = "0.4.0+sdk-1.4.341.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "eda41003dc44290527a59b13432d4a0379379fa074b70174882adfbdfd917844"
+checksum = "d9571ea910ebd84c86af4b3ed27f9dbdc6ad06f17c5f96146b2b671e2976744f"
 dependencies = [
  "bitflags 2.10.0",
 ]
@@ -2614,7 +2583,7 @@ version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6c2499c2d826531388872b2268718aed907a39bd785ab0dcfe57fab26283f92e"
 dependencies = [
- "skrifa 0.39.0",
+ "skrifa",
  "yazi",
  "zeno",
 ]
@@ -2703,16 +2672,16 @@ dependencies = [
 
 [[package]]
 name = "tiff"
-version = "0.10.3"
+version = "0.11.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "af9605de7fee8d9551863fd692cce7637f548dbd9db9180fcc07ccc6d26c336f"
+checksum = "b63feaf3343d35b6ca4d50483f94843803b0f51634937cc2ec519fc32232bc52"
 dependencies = [
  "fax",
  "flate2",
  "half",
  "quick-error",
  "weezl",
- "zune-jpeg 0.4.21",
+ "zune-jpeg",
 ]
 
 [[package]]
@@ -2885,9 +2854,9 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen"
-version = "0.2.106"
+version = "0.2.128"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0d759f433fa64a2d763d1340820e46e111a7a5ab75f993d1852d70b03dbb80fd"
+checksum = "aecb87a33d3b0c5e3b7aa46336eaf486cffafbd281b195e4c8b80d50df2351bf"
 dependencies = [
  "cfg-if",
  "once_cell",
@@ -2898,22 +2867,19 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-futures"
-version = "0.4.56"
+version = "0.4.78"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "836d9622d604feee9e5de25ac10e3ea5f2d65b41eac0d9ce72eb5deae707ce7c"
+checksum = "6ef4c5d3d2cdf5c54f4231181768f5510842e350db025faf1f7163b1030ed928"
 dependencies = [
- "cfg-if",
  "js-sys",
- "once_cell",
  "wasm-bindgen",
- "web-sys",
 ]
 
 [[package]]
 name = "wasm-bindgen-macro"
-version = "0.2.106"
+version = "0.2.128"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "48cb0d2638f8baedbc542ed444afc0644a29166f1595371af4fecf8ce1e7eeb3"
+checksum = "a690d511e3c1a8b3a55e33511e3c2c00c78415cd23650f32b808627f5696b9ed"
 dependencies = [
  "quote",
  "wasm-bindgen-macro-support",
@@ -2921,22 +2887,22 @@ dependencies = [
 
 [[package]]
 name = "wasm-bindgen-macro-support"
-version = "0.2.106"
+version = "0.2.128"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cefb59d5cd5f92d9dcf80e4683949f15ca4b511f4ac0a6e14d4e1ac60c6ecd40"
+checksum = "411e4887f0071ef2d2164a9d5fdf2d20efbef78fccd3a78b0c10a1dc5295e48a"
 dependencies = [
  "bumpalo",
  "proc-macro2",
  "quote",
- "syn 2.0.113",
+ "syn 3.0.5",
  "wasm-bindgen-shared",
 ]
 
 [[package]]
 name = "wasm-bindgen-shared"
-version = "0.2.106"
+version = "0.2.128"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cbc538057e648b67f72a982e708d485b2efa771e1ac05fec311f9f63e5800db4"
+checksum = "81941cd78d0c92026c33e5e01312845a4cb1e9af3407f9134b100dd03144103e"
 dependencies = [
  "unicode-ident",
 ]
@@ -3052,9 +3018,9 @@ dependencies = [
 
 [[package]]
 name = "web-sys"
-version = "0.3.83"
+version = "0.3.105"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9b32828d774c412041098d182a8b38b16ea816958e07cf40eec2bc080ae137ac"
+checksum = "9fbddc4a036f00ec4f18c83445bd3115cb306a91da554919a099d9222fe4a7f8"
 dependencies = [
  "js-sys",
  "wasm-bindgen",
@@ -3078,9 +3044,9 @@ checksum = "a28ac98ddc8b9274cb41bb4d9d4d5c425b6020c50c46f25559911905610b4a88"
 
 [[package]]
 name = "wgpu"
-version = "28.0.0"
+version = "30.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f9cb534d5ffd109c7d1135f34cdae29e60eab94855a625dcfe1705f8bc7ad79f"
+checksum = "527ccdf43dd5b2e8676eed9984ce00e2bbb0a1b85b70c1969dcb6cd2eb55ab9e"
 dependencies = [
  "arrayvec",
  "bitflags 2.10.0",
@@ -3088,7 +3054,7 @@ dependencies = [
  "cfg-if",
  "cfg_aliases",
  "document-features",
- "hashbrown 0.16.1",
+ "hashbrown 0.17.1",
  "js-sys",
  "log",
  "naga",
@@ -3108,9 +3074,9 @@ dependencies = [
 
 [[package]]
 name = "wgpu-core"
-version = "28.0.0"
+version = "30.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8bb4c8b5db5f00e56f1f08869d870a0dff7c8bc7ebc01091fec140b0cf0211a9"
+checksum = "14c018fce9b6270aa203c2fdd56f3cce996713534bd757e4ea58c8560b121f14"
 dependencies = [
  "arrayvec",
  "bit-set",
@@ -3119,10 +3085,11 @@ dependencies = [
  "bytemuck",
  "cfg_aliases",
  "document-features",
- "hashbrown 0.16.1",
+ "hashbrown 0.17.1",
  "indexmap",
  "log",
  "naga",
+ "naga-types",
  "once_cell",
  "parking_lot",
  "portable-atomic",
@@ -3135,66 +3102,70 @@ dependencies = [
  "wgpu-core-deps-emscripten",
  "wgpu-core-deps-windows-linux-android",
  "wgpu-hal",
+ "wgpu-naga-bridge",
  "wgpu-types",
 ]
 
 [[package]]
 name = "wgpu-core-deps-apple"
-version = "28.0.0"
+version = "30.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "87b7b696b918f337c486bf93142454080a32a37832ba8a31e4f48221890047da"
+checksum = "061f3d319a40d39d00b1ecc2c33b89fe21d4e6fe01859df3500a3a8ecccd6b68"
 dependencies = [
  "wgpu-hal",
 ]
 
 [[package]]
 name = "wgpu-core-deps-emscripten"
-version = "28.0.0"
+version = "30.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "34b251c331f84feac147de3c4aa3aa45112622a95dd7ee1b74384fa0458dbd79"
+checksum = "d98b86cf4abf524a902dd35f18ca6a3f08fc2ae9847c8f10b48e30491b1f0b86"
 dependencies = [
  "wgpu-hal",
 ]
 
 [[package]]
 name = "wgpu-core-deps-windows-linux-android"
-version = "28.0.0"
+version = "30.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "68ca976e72b2c9964eb243e281f6ce7f14a514e409920920dcda12ae40febaae"
+checksum = "7586165fd5f6d881cb9ce4bb71f40d6caab2c0f1837e3fc1d9788a197fb6004f"
 dependencies = [
  "wgpu-hal",
 ]
 
 [[package]]
 name = "wgpu-hal"
-version = "28.0.0"
+version = "30.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "293080d77fdd14d6b08a67c5487dfddbf874534bb7921526db56a7b75d7e3bef"
+checksum = "b6b7fb58561a792bc237628ba0792e332de418fefe145f13b5ed8201e6d52f58"
 dependencies = [
  "android_system_properties",
  "arrayvec",
  "ash",
  "bit-set",
  "bitflags 2.10.0",
- "block",
+ "block2 0.6.2",
  "bytemuck",
  "cfg-if",
  "cfg_aliases",
- "core-graphics-types 0.2.0",
  "glow",
  "glutin_wgl_sys",
  "gpu-allocator",
- "gpu-descriptor",
+ "hashbrown 0.17.1",
- "hashbrown 0.16.1",
  "js-sys",
  "khronos-egl",
  "libc",
  "libloading",
  "log",
- "metal",
  "naga",
+ "naga-types",
  "ndk-sys",
- "objc",
+ "objc2 0.6.4",
+ "objc2-core-foundation",
+ "objc2-core-graphics",
+ "objc2-foundation 0.3.2",
+ "objc2-metal 0.3.2",
+ "objc2-quartz-core 0.3.2",
  "once_cell",
  "ordered-float",
  "parking_lot",
@@ -3203,26 +3174,44 @@ dependencies = [
  "profiling",
  "range-alloc",
  "raw-window-handle",
+ "raw-window-metal",
  "renderdoc-sys",
  "smallvec",
+ "static_assertions",
  "thiserror 2.0.17",
  "wasm-bindgen",
+ "wayland-sys",
  "web-sys",
+ "wgpu-naga-bridge",
  "wgpu-types",
  "windows",
  "windows-core",
+ "windows-result",
+]
+
+[[package]]
+name = "wgpu-naga-bridge"
+version = "30.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2f62e73117bb7a62bfd9c5a5841438a823f6566c6442a808ee269d2d055c081"
+dependencies = [
+ "naga",
+ "wgpu-types",
 ]
 
 [[package]]
 name = "wgpu-types"
-version = "28.0.0"
+version = "30.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e18308757e594ed2cd27dddbb16a139c42a683819d32a2e0b1b0167552f5840c"
+checksum = "99dad6f1fbdbbdb4c278a6508b059d44688f5cebddf78d005a46a31340269286"
 dependencies = [
  "bitflags 2.10.0",
  "bytemuck",
  "js-sys",
  "log",
+ "naga-types",
+ "raw-window-handle",
+ "static_assertions",
  "web-sys",
 ]
 
@@ -3586,12 +3575,12 @@ dependencies = [
  "android-activity",
  "atomic-waker",
  "bitflags 2.10.0",
- "block2",
+ "block2 0.5.1",
  "bytemuck",
  "calloop",
  "cfg_aliases",
  "concurrent-queue",
- "core-foundation 0.9.4",
+ "core-foundation",
  "core-graphics",
  "cursor-icon",
  "dpi",
@@ -3858,12 +3847,6 @@ dependencies = [
  "syn 3.0.5",
 ]
 
-[[package]]
-name = "zune-core"
-version = "0.4.12"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3f423a2c17029964870cfaabb1f13dfab7d092a62a29a89264f4d36990ca414a"
-
 [[package]]
 name = "zune-core"
 version = "0.5.0"
@@ -3879,20 +3862,11 @@ dependencies = [
  "simd-adler32",
 ]
 
-[[package]]
-name = "zune-jpeg"
-version = "0.4.21"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "29ce2c8a9384ad323cf564b67da86e21d3cfdff87908bc1223ed5c99bc792713"
-dependencies = [
- "zune-core 0.4.12",
-]
-
 [[package]]
 name = "zune-jpeg"
 version = "0.5.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e35aee689668bf9bd6f6f3a6c60bb29ba1244b3b43adfd50edd554a371da37d5"
 dependencies = [
- "zune-core 0.5.0",
+ "zune-core",
 ]

Cargo.toml

@@ -29,9 +29,9 @@ edition = "2024"
 [workspace.dependencies]
 pollster = "0.4.0"
 winit = "0.30.12"
-wgpu = "28.0.0"
+wgpu = "30.0.1"
 bytemuck = "1.23.1"
-image = "0.25.6"
+image = "0.25.10"
 parley = "0.11.1"
 swash = "0.2.10"
 fxhash = "0.2.1"

core/src/event/manager.rs

@@ -135,11 +135,6 @@ impl<Rsc: HasEvents + 'static, E: Event> TypeEventManager<Rsc, E> {
         ));
     }
 
-    /// What this widget registered, without running any of it.
-    pub fn registered(&self, id: WidgetId) -> impl Iterator<Item = &E> {
-        self.map.get(&id).into_iter().flatten().map(|(e, _)| e)
-    }
-
     pub fn run_fn<'a>(
         &mut self,
         id: impl IdLike,

core/src/orientation/pos.rs

@@ -421,7 +421,7 @@ impl Display for UiRegion {
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone, Copy, PartialEq)]
 pub struct PixelRegion {
     pub top_left: Vec2,
     pub bot_right: Vec2,

core/src/render/mod.rs

@@ -186,8 +186,8 @@ impl UiRenderNode {
         for source in &registry.sources()[self.primitives.len()..] {
             let render = (source.render)(device, queue);
             let data_layout = Self::data_layout(device, source.stride);
-            let mut groups = vec![&self.shared_layout, &data_layout];
+            let mut groups = vec![Some(&self.shared_layout), Some(&data_layout)];
-            groups.extend(render.layout());
+            groups.extend(render.layout().map(Some));
             let layout = device.create_pipeline_layout(&PipelineLayoutDescriptor {
                 label: Some(source.label),
                 bind_group_layouts: &groups,
@@ -219,7 +219,7 @@ impl UiRenderNode {
             vertex: VertexState {
                 module: &module,
                 entry_point: Some("vs_main"),
-                buffers: &[PrimitiveInstance::desc()],
+                buffers: &[Some(PrimitiveInstance::desc())],
                 compilation_options: Default::default(),
             },
             fragment: Some(FragmentState {

core/src/ui/render_state.rs

@@ -34,6 +34,10 @@ impl UiRenderState {
         self.resized = true;
     }
 
+    pub fn output_size(&self) -> Vec2 {
+        self.output_size
+    }
+
     pub fn update<'a>(&mut self, root: impl Into<Option<&'a StrongWidget>>, rsc: &mut dyn UiRsc) {
         // safety mechanism for memory leaks; might wanna return a result instead so user can
         // decide whether to panic or not

examples/minimal.rs

@@ -10,11 +10,7 @@ struct State {
 }
 
 impl DefaultAppState for State {
-    fn new(
+    fn new(mut ui_state: DefaultUiState, rsc: &mut DefaultRsc<Self>, _: Proxy<Self>) -> Self {
-        mut ui_state: DefaultUiState,
-        rsc: &mut DefaultRsc<Self>,
-        _: Proxy<Self::Event>,
-    ) -> Self {
         rect(Color::RED).set_root(rsc, &mut ui_state);
         Self { ui_state }
     }

examples/tabs/main.rs

@@ -15,11 +15,7 @@ pub struct Client {
 }
 
 impl DefaultAppState for Client {
-    fn new(
+    fn new(mut ui_state: DefaultUiState, rsc: &mut DefaultRsc<Self>, _: Proxy<Self>) -> Self {
-        mut ui_state: DefaultUiState,
-        rsc: &mut DefaultRsc<Self>,
-        _: Proxy<Self::Event>,
-    ) -> Self {
         let rrect = rect(Color::WHITE).radius(20);
         let pad_test = (
             rrect.color(Color::BLUE),

examples/task.rs

@@ -11,11 +11,7 @@ struct State {
 }
 
 impl DefaultAppState for State {
-    fn new(
+    fn new(mut ui_state: DefaultUiState, rsc: &mut DefaultRsc<Self>, _: Proxy<Self>) -> Self {
-        mut ui_state: DefaultUiState,
-        rsc: &mut DefaultRsc<Self>,
-        _: Proxy<Self::Event>,
-    ) -> Self {
         let rect = rect(Color::RED).add(rsc);
         rect.task_on(CursorSense::click(), async move |mut ctx| {
             tokio::time::sleep(Duration::from_secs(1)).await;

examples/view.rs

@@ -36,11 +36,7 @@ impl Test {
 }
 
 impl DefaultAppState for State {
-    fn new(
+    fn new(mut ui_state: DefaultUiState, rsc: &mut DefaultRsc<Self>, _: Proxy<Self>) -> Self {
-        mut ui_state: DefaultUiState,
-        rsc: &mut DefaultRsc<Self>,
-        _: Proxy<Self::Event>,
-    ) -> Self {
         let test = Test::new(rsc);
 
         test.on(CursorSense::click(), move |_, rsc| {

src/default/mod.rs

@@ -1,10 +1,6 @@
 use crate::prelude::*;
 use arboard::Clipboard;
-use std::{
+use std::{marker::PhantomData, sync::Arc, time::Instant};
-    marker::{PhantomData, Sized},
-    sync::Arc,
-    time::Instant,
-};
 use winit::{
     event::{Ime, WindowEvent},
     event_loop::{ActiveEventLoop, EventLoopProxy},
@@ -29,7 +25,35 @@ pub use sense::*;
 pub use state::*;
 pub use task::*;
 
-pub type Proxy<Event> = EventLoopProxy<Event>;
+/// Sends an application's own events to its event loop. It wraps the proxy
+/// rather than being one because task updates travel the same way: what an
+/// application sends is its `Event`, not the loop's whole message type.
+pub struct Proxy<State: DefaultAppState>(EventLoopProxy<DefaultEvent<State>>);
+
+impl<State: DefaultAppState> Clone for Proxy<State> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<State: DefaultAppState> Proxy<State> {
+    pub fn send_event(&self, event: State::Event) {
+        let _ = self.0.send_event(DefaultEvent::User(event));
+    }
+}
+
+/// What the event loop carries: the application's own events, and the
+/// updates tasks send back to the ui thread.
+pub enum DefaultEvent<State: DefaultAppState> {
+    User(State::Event),
+    Update(Box<dyn TaskUpdate<DefaultRsc<State>>>),
+}
+
+impl<State: DefaultAppState> TaskQueue<DefaultRsc<State>> for Proxy<State> {
+    fn send(&self, update: Box<dyn TaskUpdate<DefaultRsc<State>>>) {
+        let _ = self.0.send_event(DefaultEvent::Update(update));
+    }
+}
 
 pub struct DefaultUiState {
     pub root: Option<StrongWidget>,
@@ -70,9 +94,8 @@ pub trait HasDefaultUiState: Sized + 'static {
 }
 
 pub trait DefaultAppState: HasDefaultUiState {
-    type Event = ();
+    type Event: Send = ();
-    fn new(ui_state: DefaultUiState, rsc: &mut DefaultRsc<Self>, proxy: Proxy<Self::Event>)
+    fn new(ui_state: DefaultUiState, rsc: &mut DefaultRsc<Self>, proxy: Proxy<Self>) -> Self;
-    -> Self;
     #[allow(unused_variables)]
     fn event(
         &mut self,
@@ -105,18 +128,14 @@ pub struct DefaultRsc<State: 'static> {
 }
 
 impl<State> DefaultRsc<State> {
-    fn init(window: Arc<Window>) -> (Self, TaskMsgReceiver<Self>) {
+    pub fn init(queue: Arc<dyn TaskQueue<Self>>) -> Self {
-        let (tasks, recv) = Tasks::init(window);
+        Self {
-        (
+            ui: Default::default(),
-            Self {
+            events: Default::default(),
-                ui: Default::default(),
+            tasks: Tasks::init(queue),
-                events: Default::default(),
+            state: Default::default(),
-                tasks,
+            _state: Default::default(),
-                state: Default::default(),
+        }
-                _state: Default::default(),
-            },
-            recv,
-        )
     }
 
     pub fn create_state<T: 'static>(&mut self, id: impl IdLike, data: T) -> WeakState<T> {
@@ -181,43 +200,32 @@ pub struct DefaultApp<State: DefaultAppState> {
     rsc: DefaultRsc<State>,
     render: UiRenderState,
     state: State,
-    task_recv: TaskMsgReceiver<DefaultRsc<State>>,
 }
 
 impl<State: DefaultAppState> AppState for DefaultApp<State> {
-    type Event = State::Event;
+    type Event = DefaultEvent<State>;
 
     fn new(event_loop: &ActiveEventLoop, proxy: EventLoopProxy<Self::Event>) -> Self {
         let window = event_loop
             .create_window(State::window_attributes())
             .unwrap();
         let default_state = DefaultUiState::new(window);
-        let (mut rsc, task_recv) = DefaultRsc::init(default_state.window.clone());
+        let mut rsc = DefaultRsc::init(Arc::new(Proxy(proxy.clone())));
-        let state = State::new(default_state, &mut rsc, proxy);
+        let state = State::new(default_state, &mut rsc, Proxy(proxy));
         let render = UiRenderState::new();
-        Self {
+        Self { rsc, state, render }
-            rsc,
-            state,
-            render,
-            task_recv,
-        }
     }
 
     fn event(&mut self, event: Self::Event, _: &ActiveEventLoop) {
-        self.state.event(event, &mut self.rsc, &mut self.render);
+        match event {
+            DefaultEvent::User(event) => self.state.event(event, &mut self.rsc, &mut self.render),
+            DefaultEvent::Update(update) => update(&mut self.state, &mut self.rsc),
+        }
+        self.request_redraw_if_needed();
     }
 
     fn window_event(&mut self, event: WindowEvent, event_loop: &ActiveEventLoop) {
-        let Self {
+        let Self { rsc, render, state } = self;
-            rsc,
-            render,
-            state,
-            task_recv,
-        } = self;
-
-        for update in task_recv.try_iter() {
-            update(state, rsc);
-        }
 
         let ui_state = state.default_state_mut();
         let input_changed = ui_state.input.event(&event);
@@ -297,11 +305,8 @@ impl<State: DefaultAppState> AppState for DefaultApp<State> {
             _ => (),
         }
         state.window_event(event, rsc, render);
-        let ui_state = self.state.default_state_mut();
+        self.request_redraw_if_needed();
-        if render.needs_redraw(&ui_state.root, rsc.widgets()) {
+        self.state.default_state_mut().input.end_frame();
-            ui_state.renderer.window().request_redraw();
-        }
-        ui_state.input.end_frame();
     }
 
     fn exit(&mut self) {
@@ -309,6 +314,15 @@ impl<State: DefaultAppState> AppState for DefaultApp<State> {
     }
 }
 
+impl<State: DefaultAppState> DefaultApp<State> {
+    fn request_redraw_if_needed(&mut self) {
+        let ui_state = self.state.default_state_mut();
+        if self.render.needs_redraw(&ui_state.root, self.rsc.widgets()) {
+            ui_state.renderer.window().request_redraw();
+        }
+    }
+}
+
 pub trait RscIdx<Rsc> {
     type Output;
     fn get(self, rsc: &Rsc) -> &Self::Output;

src/default/render.rs

@@ -22,7 +22,20 @@ impl UiRenderer {
     }
 
     pub fn draw(&mut self) {
-        let output = self.surface.get_current_texture().unwrap();
+        let output = match self.surface.get_current_texture() {
+            CurrentSurfaceTexture::Success(texture) => texture,
+            CurrentSurfaceTexture::Suboptimal(texture) => {
+                self.surface.configure(&self.device, &self.config);
+                texture
+            }
+            CurrentSurfaceTexture::Outdated | CurrentSurfaceTexture::Lost => {
+                self.surface.configure(&self.device, &self.config);
+                return;
+            }
+            CurrentSurfaceTexture::Timeout
+            | CurrentSurfaceTexture::Occluded
+            | CurrentSurfaceTexture::Validation => return,
+        };
         let view = output
             .texture
             .create_view(&TextureViewDescriptor::default());
@@ -46,7 +59,7 @@ impl UiRenderer {
 
         self.queue.submit(std::iter::once(encoder.finish()));
         self.window.pre_present_notify();
-        output.present();
+        self.queue.present(output);
     }
 
     pub fn resize(&mut self, size: &PhysicalSize<u32>) {
@@ -65,9 +78,10 @@ impl UiRenderer {
     pub fn new(window: Arc<Window>) -> Self {
         let size = window.inner_size();
 
-        let instance = Instance::new(&InstanceDescriptor {
+        let instance = Instance::new(InstanceDescriptor {
             backends: Backends::PRIMARY,
-            ..Default::default()
+            display: Some(Box::new(window.clone())),
+            ..InstanceDescriptor::new_without_display_handle()
         });
 
         let surface = instance
@@ -79,6 +93,7 @@ impl UiRenderer {
                 power_preference: PowerPreference::default(),
                 compatible_surface: Some(&surface),
                 force_fallback_adapter: false,
+                apply_limit_buckets: false,
             })
             .block_on()
             .expect("Could not get adapter!");
@@ -105,6 +120,7 @@ impl UiRenderer {
         let config = SurfaceConfiguration {
             usage: TextureUsages::RENDER_ATTACHMENT,
             format: surface_format,
+            color_space: SurfaceColorSpace::Auto,
             width: size.width,
             height: size.height,
             present_mode: PresentMode::AutoVsync,

src/default/sense.rs

@@ -52,19 +52,6 @@ impl CursorSense {
     pub fn is_dragging(&self) -> bool {
         matches!(self, CursorSense::Pressing(CursorButton::Left))
     }
-
-    /// Takes what this sense answers to out of `cursor`, so a widget below
-    /// does not also get it. Hovering takes nothing: it goes to the topmost
-    /// widget in shape, which is not a question about the input.
-    fn take(&self, cursor: &mut CursorState) {
-        match self {
-            Self::PressStart(button) | Self::Pressing(button) | Self::PressEnd(button) => {
-                *cursor.buttons.select_mut(button) = ActivationState::Off
-            }
-            Self::Scroll => cursor.scroll_delta = Vec2::ZERO,
-            Self::HoverStart | Self::Hovering | Self::HoverEnd => {}
-        }
-    }
 }
 
 #[derive(Default, Clone)]
@@ -91,14 +78,6 @@ impl CursorButtons {
         }
     }
 
-    pub fn select_mut(&mut self, button: &CursorButton) -> &mut ActivationState {
-        match button {
-            CursorButton::Left => &mut self.left,
-            CursorButton::Right => &mut self.right,
-            CursorButton::Middle => &mut self.middle,
-        }
-    }
-
     pub fn end_frame(&mut self) {
         self.left.end_frame();
         self.middle.end_frame();
@@ -185,33 +164,17 @@ impl SensorUi for UiRenderState {
         // state like thing, but local to render state, and is passed to UiRsc events so you can
         // update it there?
         let mut active = std::mem::take(&mut rsc.events_mut().get_type::<CursorSense>().active);
-        // Narrowed as it descends: a widget takes what it answers to, and
-        // what is left is what the layers below see.
-        let mut cursor = cursor;
-        let mut hovered = false;
         for layer in self.layers.indices().rev() {
-            let mut below = cursor.clone();
+            let mut sensed = false;
-            let mut hovered_here = false;
             for (id, sensor) in active.get_mut(&layer).into_flat_iter() {
                 let shape = self.active.get(id).unwrap().region;
                 let region = shape.to_px(window_size);
-                let over = cursor.exists && region.contains(cursor.pos);
+                let in_shape = cursor.exists && region.contains(cursor.pos);
-                // Hover goes to the topmost widget in shape and no further.
+                sensor.hover.update(in_shape);
-                sensor.hover.update(over && !hovered);
+                if sensor.hover == ActivationState::Off {
-                // `is_off` would be wrong here: it counts `End`, which is
-                // the one frame a hover-end handler has to run on.
-                if !over && sensor.hover == ActivationState::Off {
                     continue;
                 }
-                hovered_here |= over;
+                sensed = true;
-
-                for senses in rsc.events_mut().get_type::<CursorSense>().registered(*id) {
-                    for sense in senses.iter() {
-                        if matches(sense, &cursor, sensor.hover) {
-                            sense.take(&mut below);
-                        }
-                    }
-                }
 
                 let cursor = cursor.clone();
 
@@ -228,9 +191,7 @@ impl SensorUi for UiRenderState {
                 };
                 rsc.run_event::<CursorSense>(*id, data, state);
             }
-            hovered |= hovered_here;
+            if sensed {
-            cursor = below;
-            if hovered && !is_momentary(&cursor) {
                 break;
             }
         }
@@ -243,27 +204,20 @@ pub fn should_run(
     cursor: &CursorState,
     hover: ActivationState,
 ) -> Option<CursorSense> {
-    senses
+    for sense in senses.iter() {
-        .iter()
+        if match sense {
-        .find(|sense| matches(sense, cursor, hover))
+            CursorSense::PressStart(button) => cursor.buttons.select(button).is_start(),
-        .copied()
+            CursorSense::Pressing(button) => cursor.buttons.select(button).is_on(),
-}
+            CursorSense::PressEnd(button) => cursor.buttons.select(button).is_end(),
-
+            CursorSense::HoverStart => hover.is_start(),
-fn matches(sense: &CursorSense, cursor: &CursorState, hover: ActivationState) -> bool {
+            CursorSense::Hovering => hover.is_on(),
-    match sense {
+            CursorSense::HoverEnd => hover.is_end(),
-        CursorSense::PressStart(button) => cursor.buttons.select(button).is_start(),
+            CursorSense::Scroll => cursor.scroll_delta != Vec2::ZERO,
-        CursorSense::Pressing(button) => cursor.buttons.select(button).is_on(),
+        } {
-        CursorSense::PressEnd(button) => cursor.buttons.select(button).is_end(),
+            return Some(*sense);
-        CursorSense::HoverStart => hover.is_start(),
+        }
-        CursorSense::Hovering => hover.is_on(),
-        CursorSense::HoverEnd => hover.is_end(),
-        CursorSense::Scroll => cursor.scroll_delta != Vec2::ZERO,
     }
-}
+    None
-
-/// Whether anything is happening to the cursor beyond where it rests.
-fn is_momentary(cursor: &CursorState) -> bool {
-    cursor.scroll_delta != Vec2::ZERO || cursor.buttons.iter().any(|(_, state)| !state.is_off())
 }
 
 impl ActivationState {

src/default/task.rs

@@ -1,11 +1,5 @@
 use iris_core::HasState;
-use std::{
+use std::{pin::Pin, sync::Arc};
-    pin::Pin,
-    sync::{
-        Arc,
-        mpsc::{Receiver as SyncReceiver, Sender as SyncSender, channel as sync_channel},
-    },
-};
 use tokio::{
     runtime::Runtime,
     sync::mpsc::{
@@ -13,64 +7,52 @@ use tokio::{
         unbounded_channel as async_channel,
     },
 };
-use winit::window::Window;
-
-pub type TaskMsgSender<Rsc> = SyncSender<Box<dyn TaskUpdate<Rsc>>>;
-pub type TaskMsgReceiver<Rsc> = SyncReceiver<Box<dyn TaskUpdate<Rsc>>>;
 
 pub trait TaskUpdate<Rsc: HasState>: FnOnce(&mut Rsc::State, &mut Rsc) + Send {}
 impl<F: FnOnce(&mut Rsc::State, &mut Rsc) + Send, Rsc: HasState> TaskUpdate<Rsc> for F {}
 
+/// Hands an update from a task to the thread that owns the ui. Delivery and
+/// waking are one act: a host posts the update as a message its loop already
+/// carries, so nothing has to wake the loop separately, or claim a redraw to
+/// be looked at.
+pub trait TaskQueue<Rsc: HasState>: Send + Sync + 'static {
+    fn send(&self, update: Box<dyn TaskUpdate<Rsc>>);
+}
+
 pub struct Tasks<Rsc: HasState> {
     start: AsyncSender<BoxTask>,
-    window: Arc<Window>,
+    queue: Arc<dyn TaskQueue<Rsc>>,
-    msg_send: SyncSender<Box<dyn TaskUpdate<Rsc>>>,
 }
 
 pub struct TaskCtx<Rsc: HasState> {
-    send: TaskMsgSender<Rsc>,
+    queue: Arc<dyn TaskQueue<Rsc>>,
 }
 
 impl<Rsc: HasState> TaskCtx<Rsc> {
     pub fn update(&mut self, f: impl TaskUpdate<Rsc> + 'static) {
-        let _ = self.send.send(Box::new(f));
+        self.queue.send(Box::new(f));
-    }
-}
-impl<Rsc: HasState + 'static> TaskCtx<Rsc> {
-    fn new(send: TaskMsgSender<Rsc>) -> Self {
-        Self { send }
     }
 }
 
 type BoxTask = Pin<Box<dyn Future<Output = ()> + Send>>;
 
 impl<Rsc: HasState> Tasks<Rsc> {
-    pub fn init(window: Arc<Window>) -> (Self, TaskMsgReceiver<Rsc>) {
+    pub fn init(queue: Arc<dyn TaskQueue<Rsc>>) -> Self {
         let (start, start_recv) = async_channel();
-        let (msgs, msgs_recv) = sync_channel();
         std::thread::spawn(|| {
             let rt = Runtime::new().unwrap();
             rt.block_on(listen(start_recv))
         });
-        (
+        Self { start, queue }
-            Self {
-                start,
-                msg_send: msgs,
-                window,
-            },
-            msgs_recv,
-        )
     }
 
     pub fn spawn<F: AsyncFnOnce(TaskCtx<Rsc>) + 'static + std::marker::Send>(&mut self, task: F)
     where
         F::CallOnceFuture: Send,
     {
-        let send = self.msg_send.clone();
+        let queue = self.queue.clone();
-        let window = self.window.clone();
         let _ = self.start.send(Box::pin(async move {
-            task(TaskCtx::new(send)).await;
+            task(TaskCtx { queue }).await;
-            window.request_redraw();
         }));
     }
 }

src/harness.rs

@@ -0,0 +1,181 @@
+//! A ui with no window: build a tree, run frames, move a pointer, and read
+//! back where widgets landed.
+//!
+//! It does not draw. A claim about pixels still needs a real surface.
+
+use crate::prelude::*;
+use std::{
+    sync::{
+        Arc,
+        mpsc::{Receiver, SyncSender, sync_channel},
+    },
+    time::Duration,
+};
+
+/// There is no loop here to post to, so updates queue until the test asks
+/// for them.
+struct Queue(SyncSender<Box<dyn TaskUpdate<DefaultRsc<HarnessState>>>>);
+
+impl TaskQueue<DefaultRsc<HarnessState>> for Queue {
+    fn send(&self, update: Box<dyn TaskUpdate<DefaultRsc<HarnessState>>>) {
+        let _ = self.0.send(update);
+    }
+}
+
+/// `assert_eq!` for where a frame put a widget, written as its two corners.
+#[macro_export]
+macro_rules! assert_corners {
+    ($harness:expr, $id:expr, ($x0:expr, $y0:expr), ($x1:expr, $y1:expr)) => {
+        assert_eq!(
+            $harness.region(&$id).expect("widget drew nothing"),
+            $crate::core::PixelRegion {
+                top_left: $crate::core::util::Vec2::new($x0 as f32, $y0 as f32),
+                bot_right: $crate::core::util::Vec2::new($x1 as f32, $y1 as f32),
+            }
+        );
+    };
+}
+pub use crate::assert_corners;
+
+#[derive(Default)]
+pub struct HarnessState {
+    pub root: Option<StrongWidget>,
+}
+
+impl HasRoot for HarnessState {
+    fn set_root(&mut self, root: StrongWidget) {
+        self.root = Some(root);
+    }
+}
+
+pub struct Harness {
+    pub rsc: DefaultRsc<HarnessState>,
+    pub render: UiRenderState,
+    pub state: HarnessState,
+    updates: Receiver<Box<dyn TaskUpdate<DefaultRsc<HarnessState>>>>,
+    cursor: CursorState,
+}
+
+impl Harness {
+    /// `size` is the output in physical pixels.
+    pub fn new(size: impl Into<Vec2>) -> Self {
+        // A `TaskQueue` must be `Sync`, which `mpsc::Sender` is not; the
+        // bound that comes with `SyncSender` is far past anything a test
+        // leaves unread.
+        let (send, updates) = sync_channel(1024);
+        let rsc = DefaultRsc::init(Arc::new(Queue(send)));
+        let mut render = UiRenderState::new();
+        render.resize(size);
+        Self {
+            rsc,
+            render,
+            state: HarnessState::default(),
+            updates,
+            cursor: CursorState::default(),
+        }
+    }
+
+    pub fn size(&self) -> Vec2 {
+        self.render.output_size()
+    }
+
+    pub fn resize(&mut self, size: impl Into<Vec2>) {
+        self.render.resize(size);
+    }
+
+    /// Sets the root and lays it out, so a pointer event has something to hit.
+    pub fn set_root<T>(&mut self, widget: impl WidgetLike<DefaultRsc<HarnessState>, T>) {
+        widget.set_root(&mut self.rsc, &mut self.state);
+        self.frame();
+    }
+
+    pub fn needs_redraw(&self) -> bool {
+        self.render
+            .needs_redraw(&self.state.root, self.rsc.widgets())
+    }
+
+    pub fn apply_updates(&mut self) -> usize {
+        let mut applied = 0;
+        while let Ok(update) = self.updates.try_recv() {
+            update(&mut self.state, &mut self.rsc);
+            applied += 1;
+        }
+        applied
+    }
+
+    /// Waits for a task's first update, then applies everything waiting.
+    /// False if none arrived in time.
+    #[must_use]
+    pub fn await_update(&mut self, timeout: Duration) -> bool {
+        let Ok(update) = self.updates.recv_timeout(timeout) else {
+            return false;
+        };
+        update(&mut self.state, &mut self.rsc);
+        self.apply_updates();
+        true
+    }
+
+    /// Lays the tree out and builds its primitives.
+    pub fn frame(&mut self) {
+        self.apply_updates();
+        self.render.update(&self.state.root, &mut self.rsc);
+    }
+
+    /// Where the last frame put a widget, or `None` if it drew nothing.
+    pub fn region(&self, id: &impl IdLike) -> Option<PixelRegion> {
+        self.render.window_region(id)
+    }
+
+    pub fn move_to(&mut self, pos: impl Into<Vec2>) {
+        self.cursor.pos = pos.into();
+        self.cursor.exists = true;
+        self.sense();
+    }
+
+    pub fn leave(&mut self) {
+        self.cursor.exists = false;
+        self.sense();
+    }
+
+    pub fn press(&mut self, button: CursorButton) {
+        self.button(button).update(true);
+        self.sense();
+    }
+
+    pub fn release(&mut self, button: CursorButton) {
+        self.button(button).update(false);
+        self.sense();
+    }
+
+    /// A wheel carries no position, so this goes wherever the cursor was last
+    /// moved to -- nowhere, until it has been moved.
+    pub fn scroll(&mut self, delta: impl Into<Vec2>) {
+        self.cursor.scroll_delta = delta.into();
+        self.sense();
+    }
+
+    pub fn click(&mut self, pos: impl Into<Vec2>) {
+        self.move_to(pos);
+        self.press(CursorButton::Left);
+        self.release(CursorButton::Left);
+    }
+
+    fn button(&mut self, button: CursorButton) -> &mut ActivationState {
+        let buttons = &mut self.cursor.buttons;
+        match button {
+            CursorButton::Left => &mut buttons.left,
+            CursorButton::Middle => &mut buttons.middle,
+            CursorButton::Right => &mut buttons.right,
+        }
+    }
+
+    /// Dispatches against the layout of the last frame, which is what a
+    /// window delivers input against too.
+    fn sense(&mut self) {
+        let cursor = self.cursor.clone();
+        let size = self.render.output_size();
+        self.render
+            .run_sensors(&mut self.rsc, &mut self.state, cursor, size);
+        self.cursor.end_frame();
+    }
+}

src/lib.rs

@@ -7,6 +7,7 @@
 
 pub mod default;
 pub mod event;
+pub mod harness;
 pub mod widget;
 
 pub use iris_core as core;

src/widget/position/mod.rs

@@ -4,7 +4,7 @@ mod max_size;
 mod offset;
 mod pad;
 mod scroll;
-mod sized;
+mod set_size;
 mod span;
 mod stack;
 
@@ -14,6 +14,6 @@ pub use max_size::*;
 pub use offset::*;
 pub use pad::*;
 pub use scroll::*;
-pub use sized::*;
+pub use set_size::*;
 pub use span::*;
 pub use stack::*;

src/widget/position/set_size.rs

@@ -1,12 +1,12 @@
 use crate::prelude::*;
 
-pub struct Sized {
+pub struct SetSize {
     pub inner: StrongWidget,
     pub x: Option<Len>,
     pub y: Option<Len>,
 }
 
-impl Sized {
+impl SetSize {
     fn apply_to_outer(&self, ctx: &mut SizeCtx) {
         if let Some(x) = self.x {
             ctx.outer.x.select_len(x.apply_rest());
@@ -17,7 +17,7 @@ impl Sized {
     }
 }
 
-impl Widget for Sized {
+impl Widget for SetSize {
     fn draw(&mut self, painter: &mut Painter) {
         painter.widget(&self.inner);
     }

src/widget/ptr.rs

@@ -1,5 +1,5 @@
 use crate::prelude::*;
-use std::marker::{Sized, Unsize};
+use std::marker::Unsize;
 
 pub struct WidgetPtr {
     pub inner: Option<StrongWidget>,

src/widget/text/build.rs

@@ -1,5 +1,5 @@
 use crate::prelude::*;
-use std::marker::{PhantomData, Sized};
+use std::marker::PhantomData;
 
 pub struct TextBuilder<State, O = TextOutput, H: WidgetOption<State> = ()> {
     pub content: String,

src/widget/trait_fns.rs

@@ -31,9 +31,9 @@ widget_trait! {
         }
     }
 
-    fn sized(self, size: impl Into<Size>) -> impl WidgetFn<Rsc, Sized> {
+    fn sized(self, size: impl Into<Size>) -> impl WidgetFn<Rsc, SetSize> {
         let size = size.into();
-        move |state| Sized {
+        move |state| SetSize {
             inner: self.add_strong(state),
             x: Some(size.x),
             y: Some(size.y),
@@ -58,18 +58,18 @@ widget_trait! {
         }
     }
 
-    fn width(self, len: impl Into<Len>) -> impl WidgetFn<Rsc, Sized> {
+    fn width(self, len: impl Into<Len>) -> impl WidgetFn<Rsc, SetSize> {
         let len = len.into();
-        move |state| Sized {
+        move |state| SetSize {
             inner: self.add_strong(state),
             x: Some(len),
             y: None,
         }
     }
 
-    fn height(self, len: impl Into<Len>) -> impl WidgetFn<Rsc, Sized> {
+    fn height(self, len: impl Into<Len>) -> impl WidgetFn<Rsc, SetSize> {
         let len = len.into();
-        move |state| Sized {
+        move |state| SetSize {
             inner: self.add_strong(state),
             x: None,
             y: Some(len),

tests/draw_cost.rs

@@ -4,20 +4,19 @@
 //!
 //!     cargo test --release --test draw_cost -- --ignored --nocapture
 //!
-//! **Read the instruction count, not the clock.** Wall time here swings by 2x
+//! Wall time is the wrong number to read for anything under a few percent --
-//! between runs of one binary on this machine -- more under `cargo test` than
+//! it varied by 2x between runs of one unchanged binary where instructions
-//! run directly -- while instructions retired are stable to 0.1%:
+//! retired varied by 0.1%. Count those instead:
 //!
 //!     perf stat -e instructions:u target/release/.../draw_cost-* --ignored
 //!
-//! Measured that way on 2026-09-13, drawing each primitive through its own
+//! That is how `PrimitiveRender` was measured against a match in the renderer:
-//! `PrimitiveRender` rather than a match in the renderer costs **6
+//! 6 instructions per list drawn, against the ~5,400 wgpu spends recording
-//! instructions per list drawn**, which is 0.1% of a frame at both 256 and
+//! one.
-//! 1024 layers. Recording one list into the pass costs wgpu ~5,400.
 //!
-//! The instance is leaked on purpose. Dropping the last one makes the Vulkan
+//! The instance is leaked deliberately. A Vulkan loader may unload the driver
-//! loader unload Mesa's ICD, which faults when a thread that touched Vulkan
+//! when the last one drops, which can fault as a thread that used it exits --
-//! exits -- and libtest runs every test on a spawned thread.
+//! and every test runs on a spawned thread.
 
 use std::time::Instant;
 
@@ -30,20 +29,20 @@ use wgpu::{Color as GpuColor, *};
 
 const SIZE: u32 = 1024;
 const FRAMES: u32 = 200;
-/// Reported as the best of this many batches. The mean moves by 15% between
+/// Reported as the best of this many batches, since the mean moves by more
-/// runs on this machine, which is more than the thing being measured.
+/// than the thing being measured.
 const BATCHES: u32 = 8;
 
 fn gpu() -> Option<(Device, Queue)> {
-    // Probed rather than assumed: this machine's Vulkan device comes and goes,
+    // Probed rather than assumed: there may be no Vulkan adapter, and GL is
-    // and GL is what is left when it is gone.
+    // what is left when there is not.
-    let all = Instance::new(&InstanceDescriptor::default());
+    let all = Instance::new(InstanceDescriptor::new_without_display_handle());
     let instance = match pollster::block_on(all.request_adapter(&RequestAdapterOptions::default()))
     {
         Ok(_) => all,
-        Err(_) => Instance::new(&InstanceDescriptor {
+        Err(_) => Instance::new(InstanceDescriptor {
             backends: Backends::GL,
-            ..Default::default()
+            ..InstanceDescriptor::new_without_display_handle()
         }),
     };
     // Leaked rather than dropped: see the note at the top of the file.
@@ -58,6 +57,7 @@ fn config(format: TextureFormat) -> SurfaceConfiguration {
     SurfaceConfiguration {
         usage: TextureUsages::RENDER_ATTACHMENT,
         format,
+        color_space: SurfaceColorSpace::Auto,
         width: SIZE,
         height: SIZE,
         present_mode: PresentMode::Fifo,

tests/layout.rs

@@ -0,0 +1,34 @@
+//! Where a frame puts things, with no window to put them in.
+
+use iris::harness::{Harness, assert_corners};
+use iris::prelude::*;
+
+/// A fixed 100 wide, and the rest of the 400 to its neighbour.
+fn two_rects(h: &mut Harness) -> (WidgetId, WidgetId) {
+    let left = rect(Color::RED).width(100).add(&mut h.rsc);
+    let right = rect(Color::BLUE).add(&mut h.rsc);
+    h.set_root((left, right).span(Dir::RIGHT));
+    (left.id(), right.id())
+}
+
+#[test]
+fn a_span_gives_each_child_the_width_it_asked_for() {
+    let mut h = Harness::new((400, 200));
+    let (left, right) = two_rects(&mut h);
+
+    assert_corners!(h, left, (0, 0), (100, 200));
+    assert_corners!(h, right, (100, 0), (400, 200));
+}
+
+#[test]
+fn resizing_relays_out_against_the_new_output() {
+    let mut h = Harness::new((400, 200));
+    let (left, right) = two_rects(&mut h);
+
+    h.resize((800, 100));
+    assert!(h.needs_redraw());
+    h.frame();
+
+    assert_corners!(h, left, (0, 0), (100, 100));
+    assert_corners!(h, right, (100, 0), (800, 100));
+}

tests/pointer.rs

@@ -0,0 +1,60 @@
+//! Which widget an input reaches.
+
+use std::{cell::RefCell, rc::Rc};
+
+use iris::harness::Harness;
+use iris::prelude::*;
+
+#[test]
+fn a_press_reaches_only_the_widget_under_the_cursor() {
+    let mut h = Harness::new((400, 200));
+    let clicks = Rc::new(RefCell::new(Vec::new()));
+
+    let (on_left, on_right) = (clicks.clone(), clicks.clone());
+    let left = rect(Color::RED)
+        .width(100)
+        .on(CursorSense::click(), move |_, _| {
+            on_left.borrow_mut().push("left")
+        })
+        .add(&mut h.rsc);
+    let right = rect(Color::BLUE)
+        .on(CursorSense::click(), move |_, _| {
+            on_right.borrow_mut().push("right")
+        })
+        .add(&mut h.rsc);
+    h.set_root((left, right).span(Dir::RIGHT));
+
+    h.click((50, 100));
+    assert_eq!(*clicks.borrow(), ["left"]);
+
+    h.click((300, 100));
+    assert_eq!(*clicks.borrow(), ["left", "right"]);
+}
+
+#[test]
+fn hover_ends_when_the_cursor_leaves_the_window() {
+    let mut h = Harness::new((400, 200));
+    let hovered = Rc::new(RefCell::new(0));
+    let ended = Rc::new(RefCell::new(0));
+
+    let (h_count, e_count) = (hovered.clone(), ended.clone());
+    let widget = rect(Color::RED)
+        .on(CursorSense::HoverStart, move |_, _| {
+            *h_count.borrow_mut() += 1
+        })
+        .on(CursorSense::HoverEnd, move |_, _| {
+            *e_count.borrow_mut() += 1
+        })
+        .add(&mut h.rsc);
+    h.set_root(widget);
+
+    h.move_to((200, 100));
+    assert_eq!((*hovered.borrow(), *ended.borrow()), (1, 0));
+
+    // A second sample inside the same widget is not a second hover.
+    h.move_to((210, 100));
+    assert_eq!((*hovered.borrow(), *ended.borrow()), (1, 0));
+
+    h.leave();
+    assert_eq!((*hovered.borrow(), *ended.borrow()), (1, 1));
+}

tests/pointer_routing.rs

@@ -1,180 +0,0 @@
-//! A widget takes only what it answers to: a button over a list takes the
-//! click and leaves the scroll. These drive `run_sensors` directly, which
-//! needs no GPU and no window.
-
-use iris::prelude::*;
-use std::{cell::Cell, rc::Rc};
-
-struct SenseRsc {
-    ui: UiData,
-    events: EventManager<SenseRsc>,
-}
-
-impl UiRsc for SenseRsc {
-    fn ui(&self) -> &UiData {
-        &self.ui
-    }
-    fn ui_mut(&mut self) -> &mut UiData {
-        &mut self.ui
-    }
-    fn on_draw(&mut self, active: &ActiveData) {
-        self.events.draw(active);
-    }
-    fn on_undraw(&mut self, active: &ActiveData) {
-        self.events.undraw(active);
-    }
-    fn on_remove(&mut self, id: WidgetId) {
-        self.events.remove(id);
-    }
-}
-
-impl HasState for SenseRsc {
-    type State = ();
-}
-
-impl HasEvents for SenseRsc {
-    fn events(&self) -> &EventManager<Self> {
-        &self.events
-    }
-    fn events_mut(&mut self) -> &mut EventManager<Self> {
-        &mut self.events
-    }
-}
-
-fn cursor_at(pos: Vec2) -> CursorState {
-    CursorState {
-        pos,
-        exists: true,
-        buttons: Default::default(),
-        scroll_delta: Vec2::ZERO,
-    }
-}
-
-/// A button covering a list, on the layer above it: the list scrolls, the
-/// button clicks, and the returned flags say which fired.
-fn button_over_list() -> (UiRenderState, SenseRsc, Rc<Cell<bool>>, Rc<Cell<bool>>) {
-    let mut rsc = SenseRsc {
-        ui: UiData::default(),
-        events: EventManager::default(),
-    };
-
-    // Both cover the whole window: the button "sitting over" the list.
-    let list = rsc.ui.widgets.add_strong(Rect::new(UiColor::WHITE));
-    let list_weak = list.weak();
-    let button = rsc.ui.widgets.add_strong(Rect::new(UiColor::RED));
-    let button_weak = button.weak();
-
-    let scrolled = Rc::new(Cell::new(false));
-    let clicked = Rc::new(Cell::new(false));
-    {
-        let scrolled = scrolled.clone();
-        rsc.register_event(list_weak, CursorSense::Scroll, move |_ctx, _rsc| {
-            scrolled.set(true);
-        });
-    }
-    {
-        let clicked = clicked.clone();
-        rsc.register_event(button_weak, CursorSense::click(), move |_ctx, _rsc| {
-            clicked.set(true);
-        });
-    }
-
-    // A Stack draws each child on its own layer, in order.
-    let root = rsc
-        .ui
-        .widgets
-        .add_strong(Stack {
-            children: vec![list.any(), button.any()],
-            size: StackSize::default(),
-        })
-        .any();
-
-    let mut render = UiRenderState::new();
-    render.resize((100.0, 100.0));
-    render.update(&root, &mut rsc);
-
-    (render, rsc, scrolled, clicked)
-}
-
-#[test]
-fn a_button_over_a_list_scrolls_the_list_and_still_clicks() {
-    let (render, mut rsc, scrolled, clicked) = button_over_list();
-    let mut state = ();
-
-    let mut scroll = cursor_at((50.0, 50.0).into());
-    scroll.scroll_delta = (0.0, 10.0).into();
-    render.run_sensors(&mut rsc, &mut state, scroll, (100.0, 100.0).into());
-
-    assert!(
-        scrolled.get(),
-        "a scroll over the button must still reach the list underneath it"
-    );
-    assert!(
-        !clicked.get(),
-        "a scroll is not a click; the button must not have fired"
-    );
-
-    let mut click = cursor_at((50.0, 50.0).into());
-    click.buttons.left = ActivationState::Start;
-    render.run_sensors(&mut rsc, &mut state, click, (100.0, 100.0).into());
-
-    assert!(
-        clicked.get(),
-        "the button on top must still receive an actual click"
-    );
-}
-
-#[test]
-fn a_click_and_a_scroll_in_one_frame_go_to_different_widgets() {
-    let (render, mut rsc, scrolled, clicked) = button_over_list();
-    let mut state = ();
-
-    let mut both = cursor_at((50.0, 50.0).into());
-    both.scroll_delta = (0.0, 10.0).into();
-    both.buttons.left = ActivationState::Start;
-    render.run_sensors(&mut rsc, &mut state, both, (100.0, 100.0).into());
-
-    assert!(
-        clicked.get(),
-        "the button takes the click it registered for"
-    );
-    assert!(
-        scrolled.get(),
-        "taking the click must not take the scroll with it"
-    );
-}
-
-#[test]
-fn leaving_a_widget_still_ends_its_hover() {
-    let mut rsc = SenseRsc {
-        ui: UiData::default(),
-        events: EventManager::default(),
-    };
-    let widget = rsc.ui.widgets.add_strong(Rect::new(UiColor::WHITE));
-    let ended = Rc::new(Cell::new(false));
-    {
-        let ended = ended.clone();
-        rsc.register_event(widget.weak(), CursorSense::HoverEnd, move |_ctx, _rsc| {
-            ended.set(true);
-        });
-    }
-
-    let root = widget.any();
-    let mut render = UiRenderState::new();
-    render.resize((100.0, 100.0));
-    render.update(&root, &mut rsc);
-
-    let mut state = ();
-    render.run_sensors(
-        &mut rsc,
-        &mut state,
-        cursor_at((50.0, 50.0).into()),
-        (100.0, 100.0).into(),
-    );
-    assert!(!ended.get(), "the cursor is still on it");
-
-    let mut gone = cursor_at((50.0, 50.0).into());
-    gone.exists = false;
-    render.run_sensors(&mut rsc, &mut state, gone, (100.0, 100.0).into());
-    assert!(ended.get(), "leaving a widget ends its hover");
-}

tests/scroll.rs

@@ -0,0 +1,26 @@
+//! Scrolling moves content and stops at its ends.
+
+use iris::harness::{Harness, assert_corners};
+use iris::prelude::*;
+
+#[test]
+fn a_wheel_scrolls_the_content_and_stops_at_its_end() {
+    let mut h = Harness::new((400, 200));
+    // Twice the window's height, so there is 200 to scroll.
+    let top = rect(Color::RED).height(200).add(&mut h.rsc);
+    let bottom = rect(Color::BLUE).height(200).add(&mut h.rsc);
+    h.set_root((top, bottom).span(Dir::DOWN).scrollable());
+    h.move_to((200, 100));
+
+    // `Scroll` starts snapped to the end.
+    assert_corners!(h, top, (0, -200), (400, 0));
+
+    // The handler scales a wheel line by 50.
+    h.scroll((0, 1));
+    h.frame();
+    assert_corners!(h, top, (0, -150), (400, 50));
+
+    h.scroll((0, 10));
+    h.frame();
+    assert_corners!(h, top, (0, 0), (400, 200));
+}

tests/tasks.rs

@@ -0,0 +1,23 @@
+//! What a background task can change, and how it gets back to the ui.
+
+use std::time::Duration;
+
+use iris::harness::Harness;
+use iris::prelude::*;
+
+#[test]
+fn a_task_update_reaches_the_tree() {
+    let mut h = Harness::new((400, 200));
+    let widget = rect(Color::RED).add(&mut h.rsc);
+    h.set_root(widget.task_on(CursorSense::click(), async move |mut ctx| {
+        ctx.update(move |_, rsc| widget(rsc).color = Color::BLUE);
+    }));
+
+    h.click((200, 100));
+
+    assert!(
+        h.await_update(Duration::from_secs(5)),
+        "the task sent no update"
+    );
+    assert_eq!(h.rsc[widget].color, Color::BLUE);
+}