Handle tab drag end on pane items to insert after active item

Co-Authored-By: Kay Simmons <kay@zed.dev>

crates/gpui/src/elements/mouse_event_handler.rs

@@ -172,13 +172,16 @@ impl<Tag> Element for MouseEventHandler<Tag> {
     ) -> Self::PaintState {
         let visible_bounds = visible_bounds.intersection(bounds).unwrap_or_default();
         let hit_bounds = self.hit_bounds(visible_bounds);
+
+        self.child.paint(bounds.origin(), visible_bounds, cx);
+
+        cx.paint_stacking_context(None, |cx| {
             if let Some(style) = self.cursor_style {
                 cx.scene.push_cursor_region(CursorRegion {
                     bounds: hit_bounds,
                     style,
                 });
             }
-
             cx.scene.push_mouse_region(
                 MouseRegion::from_handlers::<Tag>(
                     cx.current_view_id(),
@@ -190,8 +193,7 @@ impl<Tag> Element for MouseEventHandler<Tag> {
                 .with_notify_on_hover(self.notify_on_hover)
                 .with_notify_on_click(self.notify_on_click),
             );
-
+        });
-        self.child.paint(bounds.origin(), visible_bounds, cx);
     }
 
     fn rect_for_text_range(

crates/gpui/src/elements/stack.rs

@@ -42,9 +42,9 @@ impl Element for Stack {
         cx: &mut PaintContext,
     ) -> Self::PaintState {
         for child in &mut self.children {
-            cx.scene.push_layer(None);
+            cx.paint_layer(None, |cx| {
                 child.paint(bounds.origin(), visible_bounds, cx);
-            cx.scene.pop_layer();
+            });
         }
     }
 

crates/gpui/src/presenter.rs

@@ -707,6 +707,16 @@ impl<'a> PaintContext<'a> {
         }
     }
 
+    #[inline]
+    pub fn paint_stacking_context<F>(&mut self, clip_bounds: Option<RectF>, f: F)
+    where
+        F: FnOnce(&mut Self),
+    {
+        self.scene.push_stacking_context(clip_bounds);
+        f(self);
+        self.scene.pop_stacking_context();
+    }
+
     #[inline]
     pub fn paint_layer<F>(&mut self, clip_bounds: Option<RectF>, f: F)
     where

crates/workspace/src/dock.rs

@@ -362,6 +362,7 @@ impl View for ToggleDockButton {
             }
         })
         .with_cursor_style(CursorStyle::PointingHand);
+        .on_
 
         if dock_position.is_visible() {
             button

crates/workspace/src/pane.rs

@@ -1373,10 +1373,12 @@ impl View for Pane {
             .with_child(
                 MouseEventHandler::<MouseNavigationHandler>::new(0, cx, |_, cx| {
                     if let Some(active_item) = self.active_item() {
+                        enum PaneContentTabDropTarget {}
+
                         Flex::column()
                             .with_child({
                                 let mut tab_row = Flex::row()
-                                    .with_child(self.render_tabs(cx).flex(1.0, true).named("tabs"));
+                                    .with_child(self.render_tabs(cx).flex(1., true).named("tabs"));
 
                                 // Render pane buttons
                                 let theme = cx.global::<Settings>().theme.clone();
@@ -1440,8 +1442,35 @@ impl View for Pane {
                                     .flex(1., false)
                                     .named("tab bar")
                             })
-                            .with_child(ChildView::new(&self.toolbar, cx).expanded().boxed())
+                            .with_child({
-                            .with_child(ChildView::new(active_item, cx).flex(1., true).boxed())
+                                let drop_index = self.active_item_index + 1;
+                                MouseEventHandler::<PaneContentTabDropTarget>::new(
+                                    0,
+                                    cx,
+                                    |_, cx| {
+                                        Flex::column()
+                                            .with_child(
+                                                ChildView::new(&self.toolbar, cx)
+                                                    .expanded()
+                                                    .boxed(),
+                                            )
+                                            .with_child(
+                                                ChildView::new(active_item, cx)
+                                                    .flex(1., true)
+                                                    .boxed(),
+                                            )
+                                            .boxed()
+                                    },
+                                )
+                                .on_up(MouseButton::Left, {
+                                    let pane = cx.handle();
+                                    move |_, cx: &mut EventContext| {
+                                        Pane::handle_dropped_item(&pane, drop_index, cx)
+                                    }
+                                })
+                                .flex(1., true)
+                                .boxed()
+                            })
                             .boxed()
                     } else {
                         enum EmptyPane {}