Integration: a shared transform box keeps the held handle's cursor (#8623)

Main's handle_at (#5405) read only the one-layer preview's gesture, so with
several layers framed the corner being dragged lost its resize pointer once
the pointer left the handle (it showed the commit pointer instead). It now
reads the shared box's gesture too, through live_gesture.

Co-authored-by: ekedal <71788463+ekedal@users.noreply.github.com>
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/ui-egui/src/tools/transform_tool/pointer.rs

@@ -316,7 +316,7 @@ pub(super) fn rotate_dir(t: &TransformSession, gesture: Option<Gesture>, p: [f64
 
 /// The handle a drag in progress holds, else the one under document point `p`.
 pub(super) fn handle_at(app: &PhotocraftApp, t: &TransformSession, p: [f64; 2], tol: f64) -> Hit {
-    app.transform_preview.as_ref().and_then(|pv| pv.gesture.map(|g| g.hit)).unwrap_or_else(|| hit(t, p, tol))
+    live_gesture(app).map(|g| g.hit).unwrap_or_else(|| hit(t, p, tol))
 }
 
 /// Cursor for hovering a document point while transforming. `xf` is the canvas's view;

crates/ui-egui/src/tools/transform_tool/tests.rs

@@ -1132,6 +1132,29 @@ fn shared_transform_detects_a_changed_layer_selection() {
     assert!(multi_selection_changed(&app, app.multi_transform.as_ref().unwrap()));
 }
 
+/// A shared box keeps the held handle's pointer for the whole drag, as a one-layer box does
+/// (#5405): dragged off its corner, the resize pointer doesn't turn into the commit one.
+#[test]
+fn a_shared_box_keeps_the_held_handles_cursor_during_a_drag() {
+    let mut app = app_with_square(64, photocraft_geom::Rect::new(8, 8, 24, 24));
+    app.ui.extras.snap = false;
+    let first = app.session.active().unwrap().active_layer.unwrap();
+    app.session.execute("layer.new.layer", json!({})).unwrap();
+    let second = app.session.active().unwrap().active_layer.unwrap();
+    app.session.execute("layer.select", json!({"layer": first.0, "mode": "add"})).unwrap();
+    begin_layers(&mut app, vec![first, second], [8.0, 8.0, 48.0, 24.0]).unwrap();
+    let xf = ViewXform::active(&app).unwrap();
+    let none = egui::Modifiers::NONE;
+    let corner = cursor(&app, &xf, [48.0, 24.0], none);
+    let far = cursor(&app, &xf, [48.0, 60.0], none);
+    assert_ne!(corner, far, "away from the box the pointer differs");
+    crate::canvas::tool_event(&mut app, ToolEvent::Down { x: 48.0, y: 24.0, pressure: 1.0 }, none);
+    crate::canvas::tool_event(&mut app, ToolEvent::Move { x: 48.0, y: 60.0, pressure: 1.0 }, none);
+    assert!(app.multi_transform.as_ref().is_some_and(|m| m.gesture.is_some()), "the shared box holds the corner");
+    assert_eq!(cursor(&app, &xf, [48.0, 60.0], none), corner, "the dragged corner keeps its pointer");
+    crate::canvas::tool_event(&mut app, ToolEvent::Up { x: 48.0, y: 60.0 }, none);
+}
+
 /// Transform Selection cannot replace a shared transform that is already open.
 #[test]
 fn transform_selection_rejects_an_open_multi_transform_without_replacing_it() {