Well, this is not a bug, but rather an annoyance.
I noticed that while was working with a large number of documents (>15).
1 st thing: if my File Explorer window is tucked up (pin button is set to vertical) and I use scroll to the next File Tab button (showed below) or keep pressing it the File Explorer (with the project explorer) would pop up and hide back and forth.
2 nd thing: I expected - if I click on next file tab arrow I get the tag retracted in full so the file name on the tag does not get truncated, but alas, I need to click an extra time to display it in full (becomes too bad for long paths).
PS: Just checked - even if the pin button is horizontal the File Explorer would try to pop up but not expand, just would come folded and that is on and off.
PS2: Ohm, and the bottom pane (find results, etc) would also jump back and forth, and I strongly think it is a bug, because if you are lucky enough to be at the stage when they are hidden - you will not be able to display them.