EGL 1.5 specification requires to not match on EGL_NATIVE_VISUAL_ID.
EGL_MESA_x11_native_visual_id extension allows us to remove this
restriction for X11, where we need to match EGL_NATIVE_VISUAL_ID to find
visuals which allow blending.
The reasoning is that on X11, compositors use the visual as "magic bit"
to decide whether to alpha-blend surface contents.
Unlike on most (all?) other windowing systems, requesting an alpha channel
for the config alone does not already imply blending on the compositor
level.
Thus, in order to allow clients to explicitly request configs with
"magic bit" and, similar to GLX, to order configs in a way so clients
not requesting alpha-blending do not get it by accident, do match
visual ids.
Note that one consequence of this is that more configs get
reported to clients.
Based on a patch by Freya Gentz <zegentzy@protonmail.com>, see
https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/2376
Signed-off-by: Robert Mader <robert.mader@posteo.de>
Signed-off-by: David Heidelberg <david.heidelberg@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9989>
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