Report consumption from run_event

`Event::consumes` says whether having run uses up what triggered it,
defaulting to no. `run_fn` already calls `should_run` per registration,
so it ors that across everything that ran and hands it back through
`run_event`. `CursorSenses` answers it with the sense it matched: a press
or a scroll is used up, hovering is not.

That drops `TypeEventManager::registered` and the second pass over a
widget's senses -- the match that decides consumption is now the same one
that decides whether the handler runs.

A cursor that is only resting still stops at the layer it is over, which
`run_event` cannot report because nothing need answer for it to be true.
It must not stop at a widget it has merely left, though, or ending a hover
above blocks the hover below: `leaving_a_widget_does_not_block_the_layer_below`
is that case, and it fails on `main` too.

tests/pointer_routing.rs

@@ -232,3 +232,34 @@ fn leaving_a_widget_still_ends_its_hover() {
     ui.run(gone);
     assert_eq!(hover.take(), [CursorSense::HoverEnd]);
 }
+
+#[test]
+fn leaving_a_widget_does_not_block_the_layer_below() {
+    let ui = &mut Ui::new();
+    let below = full(ui);
+    // Only the left half of the layer above is a widget, so the cursor can
+    // leave it without leaving the one underneath.
+    let (above, gap) = (full(ui), full(ui));
+    let below_hover = ui.listen(&below, CursorSense::HoverStart);
+    let above_hover = ui.listen(&above, CursorSense::HoverStart | CursorSense::HoverEnd);
+    let row = ui.rsc.ui.widgets.add_strong(Span {
+        children: vec![above.any(), gap.any()],
+        dir: Dir::RIGHT,
+        gap: 0.0,
+    });
+    ui.stack(vec![below.any(), row.any()]);
+
+    let on_above = ui.cursor((20.0, 50.0));
+    ui.run(on_above);
+    assert_eq!(above_hover.take(), [CursorSense::HoverStart]);
+    assert_eq!(below_hover.take(), [], "the layer above is over it");
+
+    let beside_it = ui.cursor((80.0, 50.0));
+    ui.run(beside_it);
+    assert_eq!(above_hover.take(), [CursorSense::HoverEnd]);
+    assert_eq!(
+        below_hover.take(),
+        [CursorSense::HoverStart],
+        "ending a hover above must not stop the hover below"
+    );
+}