I just noticed this bug also exists in Rhino 6 (so probably been always there). I have no idea, how I noticed it only now that I’m trying R8 evaluation.
Aaand I just found out that this bug also exists when selecting from the new Block Manager in R8 (in R6 this doesn’t happen because closing the old Block Manager window triggers the gumball). Not sure if the fix would fix both automatically so I thought I’d better mention it.