Sway window decorations can be hidden/cropped when blur is enabled

[the-blank-x]

• Swayfx Version: sway version 0.3-6acc283 (May 25 2023, branch 'master')
• Debug Log: swayfx.log
• Configuration File: sway.tar.gz (the default configuration file but with blur enabled at the end)
• Description: If blur enabled is specified in the config file, sway's window decorations are hidden/cropped when a window that draws its own window decorations client-side is tabbed. I cannot reproduce it if blur enabled is set during runtime, nor can I reproduce it with upstream sway version 1.8.1
• Steps to reproduce: Add blur enabled to the end of your sway config file and reload/restart/start sway, and either:
  • Open baobab, and make it tabbed (if the window decoration is still fully there, open its About window, then unfloat and tab it)
  • Open czkawka, and make it tabbed
• Screenshots:

[ErikReider]

Strange, the blur should only be the size of the surface...

Edit: Seems to be a issue with GTK applications. My guess would be that we forgot to account for the top CSD size?