Move the panel to the root window where the mouse click occurred.

ash/launcher/launcher_util.cc

 // 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.
 
 #include "ash/launcher/launcher_util.h"
 
 #include "ash/launcher/launcher_model.h"
 #include "ash/launcher/launcher_types.h"
+#include "ash/shell.h"
+#include "ui/aura/client/window_types.h"
+#include "ui/aura/window.h"
+#include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
 
 namespace ash {
 namespace launcher {
 
 int GetBrowserItemIndex(const LauncherModel& launcher_model) {
   for (size_t i = 0; i < launcher_model.items().size(); i++) {
     if (launcher_model.items()[i].type == ash::TYPE_BROWSER_SHORTCUT)
       return i;
   }
   return -1;
 }
 
+void MoveToEventRootIfPanel(aura::Window* maybe_panel,
+                            const ui::Event& event) {
+  if (maybe_panel->type() != aura::client::WINDOW_TYPE_PANEL)
+    return;
+  views::View* target = static_cast<views::View*>(event.target());
+  aura::RootWindow* target_root =
+      target ? target->GetWidget()->GetNativeView()->GetRootWindow() : NULL;
+  if (target_root && target_root != maybe_panel->GetRootWindow()) {
+    aura::Window* panel_container =
+        ash::Shell::GetContainer(target_root, maybe_panel->parent()->id());
+    // Move the panel to the target launcher.
+    panel_container->AddChild(maybe_panel);
+  }
+}
+
 }  // namespace launcher
 }  // namespace ash