Bug 419797

Created attachment 127355 [details]
Link to video showing the issue

SUMMARY

Firefox in Wayland mode is completely unusable. The application seems to be unresponsive as its window takes several seconds to update. Visual glitches can be perceived when positioning other windows over Firefox.

STEPS TO REPRODUCE

1. Open Firefox with the environment variable 'MOZ_ENABLE_WAYLAND' set to some value.
2. Try to interact with the application: move the mouse around, type something in the address bar... changes take several seconds to reflect in the window, although the application seems to be working properly and the mouse cursor changes with responsiveness if you hover over a text area, for example.
3. Place other windows on top of Firefox for more fun.

EXPECTED RESULT

The Firefox window is responsive and it doesn't cause visual glitches on other windows.

SOFTWARE/OS VERSIONS

Operating System: Arch Linux 
KDE Plasma Version: 5.18.4
KDE Frameworks Version: 5.68.0
Qt Version: 5.14.2
Kernel Version: 5.6.2-arch1-2
OS Type: 64-bit
Processors: 4 × Intel® Core™ i5-6200U CPU @ 2.30GHz
Memory: 11,6 GiB of RAM

Mozilla Firefox 75.0

glxinfo:
> name of display: :0
> display: :0  screen: 0
> direct rendering: Yes
> server glx vendor string: SGI
> server glx version string: 1.4
> client glx vendor string: Mesa Project and SGI
> client glx version string: 1.4
> GLX version: 1.4
> Extended renderer info (GLX_MESA_query_renderer):
>     Vendor: Intel (0x8086)
>     Device: Mesa Intel(R) HD Graphics 520 (SKL GT2) (0x1916)
>     Version: 20.0.4
>     Accelerated: yes
>     Video memory: 3072MB
>     Unified memory: yes
>     Preferred profile: core (0x1)
>     Max core profile version: 4.6
>     Max compat profile version: 4.6
>     Max GLES1 profile version: 1.1
>     Max GLES[23] profile version: 3.2
> OpenGL vendor string: Intel
> OpenGL renderer string: Mesa Intel(R) HD Graphics 520 (SKL GT2)
> OpenGL core profile version string: 4.6 (Core Profile) Mesa 20.0.4
> OpenGL core profile shading language version string: 4.60
> OpenGL core profile context flags: (none)
> OpenGL core profile profile mask: core profile
> OpenGL version string: 4.6 (Compatibility Profile) Mesa 20.0.4
> OpenGL shading language version string: 4.60
> OpenGL context flags: (none)
> OpenGL profile mask: compatibility profile
> OpenGL ES profile version string: OpenGL ES 3.2 Mesa 20.0.4
> OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20