I'm going to complain about it again (first time). I recently saw a crash log where the user had right-clicked on our application's notification area icon around the same time as my call to ThumbBarUpdateButtons - the result was a modal TrackPopupMenu call within the ThumbBarUpdateButtons call.. !!

What a complete mess - so make sure you only call ThumbBarUpdateButtons from a posted message/equivalent specifically for that purpose (at least in Windows 7 RTM). Unless you like strange (though rare) crashes, and the possibility thumb buttons being in the wrong state..