Group closing problem when enabled "Draw window frame when hovering a button"

Submitted by mas..@..mx.net

Assigned to Nick Schermer

Link to original bug (#9602)

Description

I enable "Window grouping" and "Draw window frame when hovering a button". Then open 3 calculator instances. Then I click the group and choose close for an instance (button doesn't dissapear, but it's not the main problem). After closing all instances - group button continue existing.

Version: 4.10.0