Just now noticed something that might be interesting.
I have 4k monitor.
When i want to move Toad to 50% of width (left or righ) and 100% full height, I gt again this issue with overlapped tabs.
But I was able to return to full screen and then to adpt lower panels in a way that they are shown when I put toad in 50% position (height).
I think that some of internal Toad calculations get confused in such a big change and not recognize new panel values properly.
Last but least, if you open later Toad Session browser (after that4k view) in 1920x1024 resultion (those are resolution on mine laptop) then problem is here again present.
Maybe to look in that code on such envs...because it really annoying to fix that everytime resolution changes...at least some button for now that will split panels in height (50:20:30) ...