Two desktop glitches: border color across desktop; desktop given absurd size

[karlkleinpaste]

[1] Somewhere in recent changes of the last week or so, the --border=XXX color began to appear as a line on half the display, both vertically and horizontally (top and right). It is not harmful, it is not present at all in the actual server (or so it seems), and restarting attach with a different color makes that color appear instead, always in the same place.

[2] When starting a desktop using GNOME, the initial requested size is ignored and a monster size is assigned, although the associated window is of the proper size. Upon attach, one gets the right size window with massively oversized content within. Basically, it seems the requested dimensions are scaled to the underlying large screen size.

Checking from another terminal, xrandr shows that it is using this large size but the requested size is available in the list, at the bottom:

$ DISPLAY=:19 xrandr
Screen 0: minimum 64 x 64, current 7680 x 4320, maximum 32767 x 32767
DUMMY0 connected 7680x4320+0+0 491mm x 254mm
   7680x4320     59.99* 
   5120x2880     59.99  
   4096x2304     59.99  
[ ... a couple dozen others like this elided ...]
   640x360       59.84    59.32  
   640x350       85.08  
   1856x960@50   50.00  
DUMMY1 disconnected

Forcing the original size works, and the display adjusts appropriately:
$ DISPLAY=:19 xrandr --output DUMMY0 --mode 1856x960@50

The absurd size selection does not occur with MATE or KDE -- something peculiar to GNOME is making this choice. Is GNOME being opportunistic about the largest size it sees available in RandR options?

To Reproduce
xpra start-desktop :19 --attach=no --resize-display=1856x960 --start-child=vgnome
vgnome is a script that executes /etc/X11/xinit/xinitrc.
xpra attach :19 --border=red,1

System Information:
Fedora 39 beta w/xpra r34567, local activity only (both server & client).

[totaam]

The first one is a work in progress.
I'll take a look at the other ones.

[totaam]

Could be related to #3994