Clear cursor when exiting window to avoid incorrect caching

ui/views/widget/desktop_aura/desktop_native_widget_aura.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 "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "ui/aura/client/activation_client.h"
 #include "ui/aura/client/aura_constants.h"
@@ skipping 927 matching lines @@
   if (GetWidget()->HasFocusManager() &&
       !GetWidget()->GetFocusManager()->OnKeyEvent(*event))
     event->SetHandled();
 }
 
 void DesktopNativeWidgetAura::OnMouseEvent(ui::MouseEvent* event) {
   DCHECK(content_window_->IsVisible());
   if (tooltip_manager_.get())
     tooltip_manager_->UpdateTooltip();
   TooltipManagerAura::UpdateTooltipManagerForCapture(GetWidget());
+  // This is required because the cursor is a per-thread property on Windows
+  // (not a per-window). We don't respond to WM_SETCURSOR, but instead rely on
+  // the cursor_client to call ::SetCursor appropriately. If we don't clear
+  // the cursor on exiting the widget, then the next time, the cursor client
+  // will not call ::SetCursor appropriately because it will believe it's
+  // already set the cursor for the window (and there's a cursor client per

[sky, 2013/11/22 21:26:47]

Why does the cursor client think it's already set the cursor?

+  // created per window).
+  if (event->type() == ui::ET_MOUSE_EXITED)
+    cursor_client_->SetCursor(ui::kCursorNull);
   native_widget_delegate_->OnMouseEvent(event);
   // WARNING: we may have been deleted.
 }
 
 void DesktopNativeWidgetAura::OnScrollEvent(ui::ScrollEvent* event) {
   if (event->type() == ui::ET_SCROLL) {
     native_widget_delegate_->OnScrollEvent(event);
     if (event->handled())
       return;
 
@@ skipping 154 matching lines @@
   input_method_event_filter_->SetInputMethodPropertyInRootWindow(
       root_window_->window());
   root_window_event_filter_->AddHandler(input_method_event_filter_.get());
 }
 
 void DesktopNativeWidgetAura::UpdateWindowTransparency() {
   content_window_->SetTransparent(ShouldUseNativeFrame());
 }
 
 }  // namespace views