xpra shadows 1080x1920 screen / html5 client shows partial screen

[fweng322]

Describe the bug With a special use case we're using vertical screen with resolution 1080x1920. Running xpra shadow --use-display=yes :0 --bind-tcp=0.0.0.0:33445 starts the xpra server. However when connecting to the server I could only see partial screen and no mouse/keyboard control at all.

To Reproduce Steps to reproduce the behavior:

1. xpra shadow --use-display=yes :0 --bind-tcp=0.0.0.0:33445
2. Open chrome (101.0) to connect http://this.ip:33445/

System Information (please complete the following information):

• Server OS: ubuntu 20.04
• Client OS: Windows/Debian buster
• Xpra Server Version 4.3.3
• Xpra Client Version xpra-html5 5.0-r1276-1

Additional context A screenshot is here: https://nextcloud.slat.org/index.php/s/P447B3SSBcFi5Ay you can see only middle part of the desktop is shown.

I can launch a program from the xpra menu Start->(desktop menu) but the mouse and keyboard has no effects.