We have the code that does "handled != handled" in WebPluginContainerImpl.cpp. We need to move this logic to webplugin_delegate_impl_win.cc and webplugin_delegate_impl_gtk.cc since we don't want this for Pepper plugins. This code is needed because Flash/Silverlight (only two I could test in windowless) return false even when they use the event. On Windows, Flash is sending the event to its windowed wndproc, which returns 0 when an event is handled per Windows convention. Not sure what's happening on Linux, but I verified that it's also needed.
Created attachment 50084 [details]
Comment on attachment 50084 [details]
Clearing flags on attachment: 50084
Committed r55606: <http://trac.webkit.org/changeset/55606>
All reviewed patches have been landed. Closing bug.