Plan for Xwayland 23.1

It's that time of year already when we have to start to think about a new release of Xwayland.

There's been quite a few changes that already deserve a release, but there are also pending merge requests that we may want to consider before a new yearly release.

The purpose of this is to list the things we might want to consider, it does not mean that everything listed here must be part of the new release though - we can decide to leave a pending merge request for later, and put a comment here on why we chose to do so.

Please note this is primarily intended to gather developer's feedback, it not meant as a poll for users to vote for their favorite fix/feature.

FWIW, I went quickly -i.e. I might have missed a few- through the list of MR for Xwayland and glamor and identified the following candidates:

• dix: switch scroll button emulation to multiples of increment
• present: Send a PresentConfigureNotify event for destroyed windows
• xwayland: Use {wl_,xdg-}output name for XRandR
• xwayland: fix GBM on driver without explicit modifiers
• glamor: Don't initialize on softpipe
• xwayland: Support CHERI/Morello by not storing pointers in uint64_t
• Draft: Add EI support (based on @whot's branch)
• Implement DRI3 v1.3 and per-surface dmabuf feedback
• Use linux_dmabuf v4 when available to get the DRM device
• Explicit GPU Synchronization for DRI3, Present, and Xwayland
• glamor: supports GLES3 shaders
• xwayland: Detect gbm_bo_get_fd_for_plane at runtime
• glamor: Use render node for glamor device path where possible
• xwayland: fix glamor es black windows
• glamor: fix for 8bit fonts and PointSize on GLES 2
• glamor cleanups
• glamor: fix mirrored glyphs on big-endian machines
• glamor: add glamor EGL vendor
• glamor: use glEGLImageTargetTexture2DOES during copy to update image texture
• Xwayland: Implement linux_dmabuf v4 feedback support
• Draft: xwayland: Multi DPI support via global factor rescaling [updated using properties]
• glamor: Fix xRGB->ARGB composite in certain cases
• xwayland: Implement wp_tearing_control_v1
• glamor: Fix rendering of pixmap textures backed by EGLImageKHR image
• glamor: Require and use GL_ARB_sampler_objects
• glamor: Learn about GL_EXT_blend_func_extended
• XWayland high-resolution scroll wheel support

Xwayland hi-res scroll support support would be interesting, as it would fix an historical discrepancy between compositors that causes spurious scroll events with some compositors (such as sway or kwin). Also related, we have a regression in master currently that was discovered when that change was backported in the stable branch and reverted in the stable branch only - Should we also revert commit e37eeb7a in the master branch?

/cc @daenzer @whot @ajax @anholt

PS: I also created a milestone %xwayland-23.1.0 for this purpose