I just discovered that you can press
ctrl while hovering over a frame with framestack!
This opens a "Frame Attributes" window showing you the global name of the frame in the title bar.
This also works for frames which FrameStackGlobalizer cannot resolve as you can see in the screenshot. The mouse cursor is not visible but I am hovering over the TalentMicroButtonAlert frame (highlighted green by fstack). The Frame Stack tooltip only shows the hex values (in spite of FrameStackGlobalizer) but the "Frame Attributes" window shows the global name TalentMicroButtonAlert allright.
By the way: Can anyone tell me why the fstack tooltip sometimes shows these bottommost yellow lines (fsobj...) but mostly it does not? What is this anyway and why is it not displayed at all times?