Do you play in Fullscreen? You could try switching to permanent windowed mode if you're tabbing out a lot.
Otherwise, you could try setting Click-through on your group window, or setting up the window how it "should" be. Right-clicking and "Locking" it. Then restart your game before you try to do anything else.
If you do play in Fullscreen, when you tab out, it's moving your windows around because it's loading a windowed mode layout, and probably screwing with positions.
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