There are actually at least two causes for the problems.
First, there is some erratic and excessive scrolling whenever you are at the bottom of the page. This is caused by the fix for ICE-3720. This problem had been there for as long as the fix for ICE-3720 was in. See screenshot-1 for the code change for ICE-3720. We need to revert this change (at least temporarily) to eliminate its interference.
Second, tooltip positioning within viewport was actually done already in ICE-3736. The code was later modified to accommodate the case in ICE-3745. This modification doesn't seem to work anymore after the tooltip positioning improvements in ICE-4853.
So, we need to find a way to make it work for all the above 3 cases.
How do you resize and scroll with the tooltip open? The tooltip will just disappear when you move the mouse cursor away.