Only drag or maximize / restore when event has not yet been handled.

ash/wm/panels/panel_window_event_handler.cc

Index: ash/wm/panels/panel_window_event_handler.cc
diff --git a/ash/wm/panels/panel_window_event_handler.cc b/ash/wm/panels/panel_window_event_handler.cc
index f056935accf756a0b15e0563da033ebdcad880c5..a3d5d8b87b2a7abe7226ab1c5d9f2e5808ac5951 100644
--- a/ash/wm/panels/panel_window_event_handler.cc
+++ b/ash/wm/panels/panel_window_event_handler.cc
@@ -23,7 +23,8 @@ PanelWindowEventHandler::~PanelWindowEventHandler() {
 
 void PanelWindowEventHandler::OnMouseEvent(ui::MouseEvent* event) {
   aura::Window* target = static_cast<aura::Window*>(event->target());
-  if (event->type() == ui::ET_MOUSE_PRESSED &&
+  if (!event->handled() &&
+      event->type() == ui::ET_MOUSE_PRESSED &&
       event->flags() & ui::EF_IS_DOUBLE_CLICK &&
       event->IsOnlyLeftMouseButton() &&
       target->delegate()->GetNonClientComponent(event->location()) ==
@@ -38,7 +39,8 @@ void PanelWindowEventHandler::OnMouseEvent(ui::MouseEvent* event) {
 
 void PanelWindowEventHandler::OnGestureEvent(ui::GestureEvent* event) {
   aura::Window* target = static_cast<aura::Window*>(event->target());
-  if (event->type() == ui::ET_GESTURE_TAP &&
+  if (!event->handled() &&
+      event->type() == ui::ET_GESTURE_TAP &&
       event->details().tap_count() == 2 &&
       target->delegate()->GetNonClientComponent(event->location()) ==
           HTCAPTION) {