thank you for the fix. The redrawing issue It is much better now. Only had one little glitch, which I was not able to reproduce: Dragging the second tab to the right moved the whole window (in a different speed). You can see this behavior in the first few seconds of this movie:
The jumping tab issue is still there:
In order to reproduce, I click back and forth between the last tab or open a new tab and then click on a folder inside that tab. It does not happen immediately, but after a few iterations.