I have a Solidworks Addin in which I call ICommandManager.AddCommandTab to add my own command tab. When an end-user selects my command tab, I would like to put up a PropertyManagerPage. Furthermore, when the end-user selects other command tab (i.e. exits out of my command tab), I would like to close the ProperyManagerPage and do other cleanups. I think the proper place to do this is in the event call-back method for switching command tab (entering from other tab to my tab; and exiting my tab to other tab). Is there such an event?