If you click out of SR2 while grabbing a tab when you click back on SR2 you can't move, close or click on that tab
EDIT: This only happens with pinned tabs
@AndrewGarrison for me it has to be pinned, if it's not pinned there's no problemo
Dev Notes: In designer or flight, click and hold on an inspector window's title bar.
Alt+Tab out of SR2
Click inside of another app
Go back to SR2 and the inspector dialog is hung.