JDK-8357697 : KWin/Wayland will no longer be a reparenting starting since Plasma 6.5
  • Type: Enhancement
  • Component: client-libs
  • Sub-Component: java.awt
  • Priority: P4
  • Status: Open
  • Resolution: Unresolved
  • OS: linux
  • CPU: generic
  • Submitted: 2025-05-23
  • Updated: 2025-05-26
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tbdUnresolved
Description
A DESCRIPTION OF THE PROBLEM :
We'd like to inform you that the X11 window manager in kwin_wayland compositor will no longer re-parent windows in Plasma 6.5. Note that kwin_x11 will still be a re-parenting window manager.

It looks like AWT has a hardcoded list of non-reparenting window managers. If isNonReparentingWM() returns a wrong value, it can result in windows not being rendered as expected, which we currently observe in the dev branch of kwin.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
- Build latest kwin
- Run jdownloader

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Jdownloader is shown as expected
ACTUAL -
Jdownloader has blank window contents because https://github.com/openjdk/jdk/blob/68ee06f0c9ec420cb1a60e0b361971372b18b82b/src/java.desktop/unix/classes/sun/awt/X11/XDecoratedPeer.java#L812-L817 fails with kwin now.