Refresh rates with multiple monitors

Joe M brainsnacks at
Tue Jun 13 01:11:44 UTC 2023

Hi, I was wondering about the internals of Wayland (wl_compositor?) with multiple physical screens/displays attached. I'm using EGL so if those details are contextual to the answer please include if possible.
As I understand, there is one global wl_display. Is there always one wl_compositor too?
I'm able to create a surface in two different apps (or multiple instance of the same app), and call "set_fullscreen" on each one. Wayland (or, weston, I guess?) does the right thing and puts them on separate physical screens.
Now, eglSwapBuffers takes as parameters the EGLDisplay and the EGLSurface. Is the vsync that the two apps observe at all interdependent, as a result of the display singleton?
If one monitor's mode is 30Hz and the other 60Hz, will both apps be constrained to the 30hz refresh?
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