got it thx!

OK I see. 

The issue is, if the window is inactive, there is no easy way to reach the group thumbnails - I have to click the icon twice and with a bit of delay between the clicks which is very distracting.

I can see no reason why hover will not show the thumbnails in all cases (active or not etc). Also/alternatively perhaps the delay can be removed so that double clicking will show the thumbnails.

Thank you for great software :)