I just discovered a problem that could have lead to a pretty darn serious bug in my application. It appears that the PrimaryWindowChanged event for the TabbedMdiHost is not fired when you right click on it instead of left clicking, but the clicked document IS activated. I use this event to control which file is currently active, so while the content of the newly selected file is displayed, my application will believe that another OpenFile object is currently the one active and save to that filename!
Since the document window is being activated it from a right click, I can only assume that the event not firing is indeed a bug? All you need to reproduce it is a TabbedMdiHost, a PrimaryWindowChanged and a mouse with more than one button :D