(https://i.imgur.com/Tswor0E.gif)
When the dialog is minimized, the part that was outside will remain as an afterimage.
I think we should dirty the area where the dialog was when the minimize is performed.
Good catch, must be there for ages. Also it does not happen with all paksets, only if they do not use the outside graphic for the outside ...
r11106 fixes this.
Thanks. I have confirmed that it is fixed.