WinKey is not "pass through"

[stdedos]

Describe the bug

Also, releasing the key seems to leave "stale modifiers" on:

When restarting with -d keyboard:

Something comes up, but it looks weird. Also, after restarting the shadow server (for the -d keyboard) "it works" (i.e., Start Menu is triggered), but the Keyboard window above shows weird things 😕

Here's the -d keyboard log: xpra.log (too long for pasting it) the ONLY think I've pressed while explicitly focused on the xpra window was WinKey.

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.

[stdedos]

Also, this looks like a heisenbug: Activating -d keyboard to observe it seems to make the bug go away 😕