When switching to thumbnail connector by pressing syskey + f9, I think the current tab thumbnail should be preselected. Or at least the upper left thumbnail. right now none is selected and you even have to press to the right once to select the upper left thumbnail.
edit: I also just found anothor minor bug: If RDTabs is a maximized window: When pressing syskey + f11, it switches into fullscreen mode. Because the clientarea grows, there appear grey borders at the top and the bottom of the connected desktop. That's fine. When pressing syskey + f11 again, the clientarea shrinks again, but the border don't disappear. Instead, the clientare is shifted a bit downwards and the border aboce is still visible and the bottom of the clientarea is cut off.