Fix panel resize (#3707)

* [x] Reposition right dock handle
* [x] Handle mouse events correctly for drag and drop
* [x] Prevent drag events from passing through the resize handle to the
draggable items in the panels (channels, files)
* [x] Stop the editor gutter from stealing mouse move events

crates/editor2/src/element.rs

@@ -564,8 +564,6 @@ impl EditorElement {
                     );
                 }
             }
-
-            cx.stop_propagation();
         } else {
             update_go_to_definition_link(editor, None, modifiers.command, modifiers.shift, cx);
             hover_at(editor, None, cx);