shadow: scaling down and up the client changes server's X dimensions

[stdedos]

Describe the bug

Under no circumstances should a shadow display (created via client's xpra shadow ssh:// or "just found initialized and connected") should allow touching the X server resolution.

2024-06-26 23:13:14,178 shadow server: setting default keymap translation
2024-06-26 23:13:16,262 Warning: not adding duplicate printer 'PDFCreator'
2024-06-26 23:13:16,262 Warning: not adding duplicate printer 'OneNote (Desktop)'
2024-06-26 23:13:20,758 client   3 @13.092 server is not responding, drawing spinners over the windows
2024-06-26 23:13:21,004 client   3 @13.342 server is OK again
2024-06-26 23:13:29,653 client   3 @21.983 window 1 has been moved to monitor 1: LG IPS234 1920x1080 at 2560,436
2024-06-26 23:14:32,511 client   3 @24.842 window 1 has been moved to monitor 0: Samsung C32JG5x 2560x1440 at 0,0
2024-06-26 23:14:42,827 client   3 @35.155 window 1 has been moved to monitor 1: LG IPS234 1920x1080 at 2560,436
2024-06-26 23:14:52,981 client   3 @45.311 setting scaling to 67%:
2024-06-26 23:14:52,981 client   3 @45.311 sending updated screen size to server: 6727x2276
2024-06-26 23:14:52,981 client   3 @45.311   Default (1185x401 mm - DPI: 144x144)
2024-06-26 23:14:52,982 client   3 @45.311     Samsung C32JG5x  3844x2162 at    0x0    (697x392 mm - DPI: 140x140) workarea: 3844x2102
2024-06-26 23:14:52,982 client   3 @45.311     LG IPS234        2883x1622 at 3844x655  (510x290 mm - DPI: 144x142) workarea: 2883x1562 at 3844x655
2024-06-26 23:14:53,820 Error: failed to set new screen size
2024-06-26 23:14:54,641 Warning: tried to set resolution to 6727x2276
2024-06-26 23:14:54,642  and ended up with 1920x1200
2024-06-26 23:14:54,642 received updated display dimensions
2024-06-26 23:14:54,642 client display size is 6727x2276
2024-06-26 23:14:54,642   Default 4480x1516 (1185x401 mm - DPI: 96x96) workarea: 4480x1476
2024-06-26 23:14:54,642     Samsung C32JG5x  2560x1440 at    0x0    (697x392 mm - DPI: 93x93) workarea: 2560x1400
2024-06-26 23:14:54,642     LG IPS234        1920x1080 at 2560x436  (510x290 mm - DPI: 96x95) workarea: 1920x1040 at 2560x436
2024-06-26 23:14:55,071 DPI set to 96 x 96
2024-06-26 23:27:20,766 Warning: CLIPBOARD selection request for 'TARGETS' timed out
2024-06-26 23:27:20,767  request 4
2024-06-26 23:27:20,881 Warning: CLIPBOARD selection request for 'TARGETS' timed out
2024-06-26 23:27:20,882  request 5
2024-06-26 23:30:18,897 client   3 @11.233 window 1 has been moved to monitor 0: Samsung C32JG5x 2560x1440 at 0,0
2024-06-26 23:30:24,254 client   3 @16.592 setting scaling to 100%:
2024-06-26 23:30:24,256 client   3 @16.592 sending updated screen size to server: 4480x1516
2024-06-26 23:30:24,257 client   3 @16.592   Default (1185x401 mm - DPI: 96x96) workarea: 4480x1476
2024-06-26 23:30:24,257 client   3 @16.592     Samsung C32JG5x  2560x1440 at    0x0    (697x392 mm - DPI: 93x93) workarea: 2560x1400
2024-06-26 23:30:24,257 client   3 @16.592     LG IPS234        1920x1080 at 2560x436  (510x290 mm - DPI: 96x95) workarea: 1920x1040 at 2560x436
2024-06-26 23:30:26,046 server virtual display now set to 4480x1516
2024-06-26 23:30:26,047 received updated display dimensions
2024-06-26 23:30:26,047 client display size is 4480x1516
2024-06-26 23:30:26,047   Default (1185x401 mm - DPI: 96x96) workarea: 4480x1476
2024-06-26 23:30:26,047     Samsung C32JG5x  2560x1440 at    0x0    (697x392 mm - DPI: 93x93) workarea: 2560x1400
2024-06-26 23:30:26,047     LG IPS234        1920x1080 at 2560x436  (510x290 mm - DPI: 96x95) workarea: 1920x1040 at 2560x436
2024-06-26 23:30:26,456 DPI set to 96 x 96 (wanted 144 x 144)
2024-06-26 23:30:26,456  you may experience scaling problems, such as huge or small fonts, etc
2024-06-26 23:30:26,456  to fix this issue, try the dpi switch, or use a patched Xorg dummy driver
2024-06-26 23:30:26,469 capture using XImageCapture
2024-06-26 23:30:26,480 capture using XImageCapture
2024-06-26 23:31:00,940 capture using XImageCapture
2024-06-26 23:31:00,949 capture using XImageCapture

To Reproduce
Steps to reproduce the behavior:

1. server command
2. client command
3. specific action to trigger the bug

System Information (please complete the following information):

• Server OS: Ubuntu 20.04.6 LTS
• Client OS: Microsoft Windows [Version 10.0.18363.836]
• Xpra Server Version: (see above)
• Xpra Client Version: (see above)

Additional context
Add any other context about the problem here.
Please see "reporting bugs" in the wiki section.