Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

Electron Version

12.0.4

What operating system are you using?

Other Linux

Operating System Version

Kubuntu 21.04

What arch are you using?

x64

Last Known Working Electron version

No response

Expected Behavior

VS Code draws just the client-side custom titlebar, no system title bar is drawn from the compositor side.

Actual Behavior

VS Code draws both system and custom client-side titlebars at the same time.

Testcase Gist URL

No response

Additional Information

According to THIS comment, either Electron asks KWin to draw a titlebar, or KWin decides on its own to draw the titlebar.

So i'm moving down the stack by one and filing a bug at Electron.

VS Code is started with the following command line in order to use Wayland implementation: /usr/share/code/code --enable-features=UseOzonePlatform --ozone-platform=wayland --no-sandbox --unity-launch %F
VS Code info:

Version: 1.56.2
Commit: 054a9295330880ed74ceaedda236253b4f39a335
Date: 2021-05-12T16:45:26.313Z
Electron: 12.0.4
Chrome: 89.0.4389.114
Node.js: 14.16.0
V8: 8.9.255.24-electron.0
OS: Linux x64 5.11.0-17-lowlatency

Kubuntu info:

Operating System: Kubuntu 21.04
KDE Plasma Version: 5.21.90
KDE Frameworks Version: 5.82.0
Qt Version: 5.15.2
Kernel Version: 5.11.0-17-lowlatency (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i5-8250U CPU @ 1.60GHz
Memory: 7,6 GiB of RAM
Graphics Processor: Mesa Intel® UHD Graphics 620