End the hover of a widget that gets covered

Breaking out of the layer loop left every sensor below the consuming
layer untouched, so one that was hovered stayed hovered: moving onto a
widget in a layer above never ended the hover of what it covered, and
nothing ever would.

Consumption now carries into the hit test rather than stopping the walk.
A covered widget is simply not in shape, so its hover ends and its
`HoverEnd` runs; `should_run` already refuses non-position senses once
the hover is not on, so nothing else reaches it. It is applied after a
layer rather than during one, so senses on the same layer still do not
block each other.

src/default/sense.rs

@@ -183,12 +183,16 @@ impl SensorUi for UiRenderState {
         // update it there?
         let mut active = std::mem::take(&mut rsc.events_mut().get_type::<CursorSense>().active);
         let position_only = cursor.position_only();
+        let mut consumed = false;
         for layer in self.layers.indices().rev() {
-            let mut consumed = false;
+            let mut consumed_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 in_shape = cursor.exists && region.contains(cursor.pos);
+                // Once a layer above has taken the input, everything under it
+                // is covered rather than skipped: it is not hovered, so a
+                // widget that was gets to end its hover.
+                let in_shape = !consumed && cursor.exists && region.contains(cursor.pos);
                 sensor.hover.update(in_shape);
                 if sensor.hover == ActivationState::Off {
                     continue;
@@ -212,11 +216,11 @@ impl SensorUi for UiRenderState {
                 // hovering does not reach through one -- but not at a widget
                 // it has just left, which is here only to end its hover.
                 let answered = rsc.run_event::<CursorSense>(*id, data, state);
-                consumed |= answered || (position_only && in_shape);
-            }
-            if consumed {
-                break;
+                consumed_here |= answered || (position_only && in_shape);
             }
+            // Applied after the layer, never during it: senses on one layer
+            // do not block each other.
+            consumed |= consumed_here;
         }
         rsc.events_mut().get_type::<CursorSense>().active = active;
     }