better support for ui action simulation

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74162 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
notify the event loop that synthesized events are on the queue, wait for them to be available, also on OSX a double click has to be synthesized slightly differently

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74163 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775