Fire an event when a menu list option becomes unselected.

Source/modules/accessibility/AXMenuListPopup.h

 /*
  * Copyright (C) 2010 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 40 matching lines @@
     virtual LayoutRect elementRect() const override { return LayoutRect(); }
     virtual AccessibilityRole roleValue() const override { return MenuListPopupRole; }
 
     virtual bool isVisible() const override;
     virtual bool press() const override;
     virtual void addChildren() override;
     virtual void childrenChanged() override;
     virtual bool computeAccessibilityIsIgnored() const override;
 
     AXMenuListOption* menuListOptionAXObject(HTMLElement*) const;
+
+    int m_activeIndex;

[Mike West, 2015/03/19 12:34:21]

This would be better as `unsigned`, as allowing negative indices into arrays is
not a wonderful idea. But, looking at HTMLSelectElement, there doesn't seem to
be anything else you could hook into. That's unfortunate. :/

Would you mind adding a note about `-1`'s magicness?

[dmazzoni, 2015/03/20 04:56:36]

Good idea, done.

 };
 
 DEFINE_AX_OBJECT_TYPE_CASTS(AXMenuListPopup, isMenuListPopup());
 
 } // namespace blink
 
 #endif // AXMenuListPopup_h