floooh
Investigate: on X11, key repeat seems to interfere with mouse lock
...when pressing 'm', no mouse movement is reported. In other code, the mouse lock feature works as expected though (e.g. cgltf-sapp.c and doom-sokol).
(to reproduce in the updated events-sapp: toggle mouse lock by pressing m, then while mouse lock is active keep pressing another key - the mouse movement events will stop, and sometimes 'sticks' even after the key is released until a mouse button is pressed).
...it works when changing events-sapp.c to toggle mouse lock on off instead of keeping the 'm' key pressed. The mouse reporting somehow seems to interfere with key repeat?
This seems to be a general X11 and XWayland problem: even on a regular desktop and without any sokol app running, mouse movement (via the touchpad) stops while a key is pressed (might be the setting that the touchpad is disabled during text input as alternative to a properly working palm detection).