Add retained paints and shared text selection

core/src/ui/active.rs

@@ -1,5 +1,6 @@
 use crate::{
-    LayerId, MaskIdx, MoveIdx, PrimitiveHandle, Size, TextureHandle, UiRegion, WidgetId, util::Vec2,
+    LayerId, MaskIdx, MoveIdx, PaintId, PrimitiveHandle, Size, TextureHandle, UiRegion, WidgetId,
+    util::Vec2,
 };
 
 #[derive(Debug)]
@@ -8,6 +9,10 @@ pub struct ActiveData {
     pub region: UiRegion,
     pub parent: Option<WidgetId>,
     pub textures: Vec<TextureHandle>,
+    /// Paint slots retained by this draw. The GPU primitive stores only the
+    /// slot index, so these handles are what prevent a live primitive from
+    /// observing a recycled paint.
+    pub paints: Vec<PaintId>,
     pub primitives: Vec<PrimitiveHandle>,
     pub children: Vec<WidgetId>,
     pub size_dependencies: Vec<WidgetId>,