Bug 2196702

If Gnome session locks the screen, after the screen is unlocked, the windows that have been snapped together previously (by pressing Shift while moving them) are ever so slightly overlapping. It's only by a few pixels and at first I thought I must have been imagining it, but after using this setup for a few days, it is definitely the case.

mutter-44.1-1.fc38.x86_64 (i.e. Fedora 38 on x86_64), on Wayland (I do not use X11 any more)

Reproducible: Always

Steps to Reproduce:
1. Start Firefox, position it on external monitor in top left corner by pressing Shift key when dragging the window.
2. Open Terminal or Console and position them immediately to the right of Firefox windows, again by pressing Shift while moving.
3. Repeat with some more Terminal/Console windows.
4. Let Gnome lock the session.
5. Unlock the session and check windows on external monitor, which are now ever so slightly overlapping.
6. Repeating this a few times will make the problem worse and some text in terminals will become invisible.
Actual Results:  
Windows either grow or change position unexpectedly.

Expected Results:  
Windows should stay exactly the same.

The hardware is ThinkPad T450s, which has 1920 x 1080 resolution on it built in panel (i.e not high DPI). The external monitor is Acer KG281K (i.e. 4k - ergo high DPI) and it is running at 3840 x 2160 at 60 Hz. I don't really know whether this has anything to do with it, but I thought I'd mention it just in case.

I am attaching two screenshots. One showing Console overlapping with Firefox, after I unlocked the session and while filing this bug. The next screenshot is me repositioning Console windows again, by moving them and pressing Shift, so that they snap back to Firefox edge.![overlap-after-unlock](/uploads/1cb2c29ef8afc10c689e6c66ab068945/overlap-after-unlock.png)