Clicking two mouse buttons at the same causes the crash. This is because there's an assert that requires there to be only one of a widget in the update list. Clicking two or more mouse buttons at the same time attempts to register an update for the widget before the previous update was carried out. I've changed it so that it will do nothing if it finds the widget is already in the update list. The crash does not occur for me now in revision 931 branch 0.3.x.
Please change the topic title to add [Fixed rev931] if you can confirm. Thanks.
