1) Open a number of resources all across the screen:

2) Open a new resource by dragging it to a second panel at the right half of the screen.
3) Close that right panel again.
4) Make sure another tab than the first is at the top. (This step needs further testing. Having the first tab active seems to reduce rearrangement.)
5) Go to Layouts and click the 'one tile icon'. (Dragging it to the shortcut bar simplifies repeated testing.)
>> The tabs rearrange themselves:

It is bad enough that tabs rearrange themselves when you first float and then redock resources, but this?? I'm essentially just widening the panel, albeit with another method than manually dragging it. There is no reason whatsoever for Logos to rearrange things.
(Since I'm always using a full screen layout whenever possible, due to the large font size I need, and since manually dragging a panel from half to full screen tends to take me a minute or more, with multiple beachballs and the panel jumping back and forth to various widths, I was trying to find a faster way to enlarge it. If it hadn't been for this bug, I would have found one.)