I can reproduce the problem in this way:
After opening 9 (or more) windows (eg. sql windows, program windows) a slider appears in order to navigate trough all entries of window list.
Fist place the slider to top (entry for window 9 is not on screen) and execute a select in window 2 - all is fine. But if you
place slider to bottom (entry for window 2 is still on screen) and ounce again execute statement in window 2, something is happend with the window list.
This similar problem can be shown with a floating list: If you add so many windows, that the list can not be shown comletely on the screen you can see a slider for a moment but then it flickers and the slider disappears. I thin the 2 problems are related but the 2. is not relevant in real live using (or are their users open 40+ cuncurent windoes?).