How to clamp tooltip to the screen?

[Lybrial]

How can I setup the tooltip to clamp to the screen?
It occurs to me that after some time playing the tooltips are starting to leave the screen.
I have already spent weeks (im not kidding) trying to find the problem but I cant find
the source and I also cant find a solution or a workaround.

Do you guys have an idea? Most of you are much more experienced than I am.