Alt+Tab on remote: is there anything else beyond grabbing the keyboard?

[charlescanato]

This is my first day with xpra - and what a piece of software! However, Alt+Tab, by what I have read around, should be working. After I grab the keyboard (Ctrl+Menu), indeed Alt+Tab is not sent to client (Win7) - and it shouldn't, but remote host behaves as if has only received a Tab.

I didn't want to create this as a bug, as I'm pretty sure I'm one of the few (if any) who can't use Alt+tab to go back and forth from my other applications on the client. I just didn't notice yet what I might be doing wrong.

To Reproduce
Steps to reproduce the behavior:

1. xpra shadow :0 --bind-tcp=0.0.0.0:18500 --daemon=no --opengl=no --speaker=off --microphone=off (first times I just used the simple shadow command directly from the client)
2. xpra_cmd.exe --env=XPRA_EMULATE_ALTGR=0 attach tcp://192.168.0.23:18500 --opengl=no --speaker=off --microphone=off (I got the env from some other issue, while trying anything - I also turned off sound and OpenGL based on some tests I've saw in other issues)
3. Ubuntu desktop window is opened totally ok - I have been using Xpra's toolbox "Keyboard State Tool" for my tests
4. Grab the keyboard, if not already using Ctrl+Menu
5. Press and hold Alt-L
6. 
7. Press and release Tab
8. 
9. As can be seen in the screenshot, before Tab goes down, Alt is released, and there's also a ghost Control_L added - which, of course, was never pressed

System Information (please complete the following information):

• Server OS: Ubuntu 22.04 LTS with Kubuntu
• Client OS: Windows 7
• Xpra Server Version: v5.0-r32495 beta
• Xpra Client Version: v5.0-r32489 (initially used v4.4.3-r0, same behavior)

I have AutoHotKey running a few keys - closing it and restarting everything also does not change the scenario.

Is there something really basic I'm missing?

[totaam]

That should work.

indeed Alt+Tab is not sent to client (Win7) - and it shouldn't

The fact that Alt+Tab is intercepted is a good sign.
Don't use XPRA_EMULATE_ALTGR=0, it will cause extra keys to be pressed / removed.
The spurious Control_L key events are a "feature" of key events on MS Windows.
Can you post the server log when running with -d keyboard?
(just the bit where you press Alt+Tab as it will be huge otherwise)

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@charlescanato Edit: oh wait, you're using shadow mode on the server... I have never tested that.
You may be able to get it to work with --keyboard-layout=auto on the server, as per
#2630 (comment)