Issues with changing title tab length on stacked windows

[humdinger]

This is hrev44214.

• Open Web+ with ​http://www.haiku-os.org
• Open /boot/home
• Stack those windows

• Click on the link to the user guide -> the title tab gets wider, drawing over the stacked home window title. Also, see in the following shot that the Screenshot app that normally fills the background transparent, shows my orange background in the part that should be occupied with the moved home window tab.

• Switch to the home window and back again to have it redrawn.
• Go back in Web+ -> the title gets narrower, the home titletab is redrawn, but the old position isn't. Switching Workspaces leave that not-redrawn area.

[humdinger]

stack two windows

[humdinger]

tab getting wider

[humdinger]

tab getting narrower

[X512]

duplicate of #8569.

[humdinger]

Missed that, thanks!