Attach panel while dragging to bring it in front of other panels.

ash/wm/workspace_controller.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ASH_WM_WORKSPACE_CONTROLLER_H_
 #define ASH_WM_WORKSPACE_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "ash/wm/workspace/workspace_types.h"
 #include "base/basictypes.h"
@@ skipping 24 matching lines @@
   WorkspaceWindowState GetWindowState() const;
 
   void SetShelf(ShelfLayoutManager* shelf);
 
   // Sets the active workspace based on |window|.
   void SetActiveWorkspaceByWindow(aura::Window* window);
 
   // Returns the container window for the active workspace, never NULL.
   aura::Window* GetActiveWorkspaceWindow();
 
+  WorkspaceEventHandler* GetEventHandlerForWindow(aura::Window* window);

[sky, 2013/03/14 20:34:46]

I have tried to keep the surface area of API exposed by the workspace code very
narrow. I don't want to start openning this up.

[flackr, 2013/03/14 20:42:04]

I could cast it to a ToplevelWindowEventHandler* before returning it if that
would help.

+
   // See description in WorkspaceManager::GetParentForNewWindow().
   aura::Window* GetParentForNewWindow(aura::Window* window);
 
   // Starts the animation that occurs on first login.
   void DoInitialAnimation();
 
   // aura::client::ActivationChangeObserver overrides:
   virtual void OnWindowActivated(aura::Window* gained_active,
                                  aura::Window* lost_active) OVERRIDE;
 
  private:
   friend class WorkspaceControllerTestHelper;
 
   aura::Window* viewport_;
 
   scoped_ptr<WorkspaceManager> workspace_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkspaceController);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_CONTROLLER_H_