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

ash/launcher/launcher.cc

Index: ash/launcher/launcher.cc
diff --git a/ash/launcher/launcher.cc b/ash/launcher/launcher.cc
index 09af40c120a680d59919a1367617e9fa7430459d..3c9a2d9735f6b94dda02204136ec866174df9b11 100644
--- a/ash/launcher/launcher.cc
+++ b/ash/launcher/launcher.cc
@@ -361,7 +361,11 @@ gfx::Rect Launcher::GetScreenBoundsOfItemIconForWindow(aura::Window* window) {
 void Launcher::ActivateLauncherItem(int index) {
   const ash::LauncherItems& items =
       launcher_view_->model()->items();
-  delegate_->ItemClicked(items[index], ui::EF_NONE);
+  ui::MouseEvent event(ui::ET_MOUSE_PRESSED,
+                       gfx::Point(),
+                       gfx::Point(),
+                       ui::EF_NONE);
+  delegate_->ItemClicked(items[index], event);
 }
 
 void Launcher::CycleWindowLinear(CycleDirection direction) {