Hi Matt,
Thanks again for your assistance. I am thinking you misunderstand . . . the behavior is not revit with my addin, the behavior is revit, and it affects my addin: when I select something in the project browser, the revit ribbon is then unresponsive . . . all of the revit ribbon, not just the addins panel, but the architecture, modify, annotate, manage, etc, the entire revit ribbon. I don't remember this being the case in Windows 7, but I cannot verify.