Mutter 3.36 request exact match of wl_surface/wl_subsurface size so we need to respect wl_surface size (GtkWidget size) and create a wl_subsurface with the same size.

Mutter 3.36 requests exact match of wl_surface/wl_subsurface size so we need to respect
wl_surface size (GtkWidget size) and create a wl_subsurface with the same size.

It's only a requirement when either tiled or maximized, and recommended when fullscreen (you should get a black border if you don't match it when fullscreen). For floating (non-tiled, non-maximized, not-fullscreen), you don't need to respect it, and sometimes can't (e.g. too small), but still should if you don't have a valid reason not to. An example here is gnome-terminal which resizes only according to the character grid. This is completely valid when the window is floating.

https://hg.mozilla.org/mozilla-central/rev/1b0e41d62723

Any chance to have that backported that late for Firefox 75?

I'd like to keep it in nightly for some time to test it. But it fixes it for Basic compositor only, I haven't time to check/fix that to WebRedner/GL yet so please test with basic compositor enabled.

I may backport it to Fedora Firefox 74/75 builds as Fedora ships Wayland by default on Fedora 31/32.

We're on the last week of beta for 75, I think this should ride the trains.

Okay, I'll backport that to Fedora then.