Cannot click on the icon flyouts in the left panel

And similarly, still can’t close the modeless windows clicking on the X in the upper right corner.

Is there any key command for the grace notes button as well (like Alt+I for insert mode)?

Yes! On my French keyboard, it’s /
The key left to the triplets one. And alt-that key changes appoggiatura into acciaccatura (and vice versa)

Great, thanks