Wayland keyboard::enter doesn't pass a list of held keys as defined by the protocol
The keyboard enter handler never receives a list of held keys.
In other Wayland compositors KDE plasma, Sway and River, this works as expected but not in gnome-shell.
This means it's not possible to know which modifier keys are held when the window is activated (left/right modifiers for e.g.). This is useful to track held keys that can be refreshed when a window is activated.
In gnome-shell, an empty list is always passed to the window.
The broadcast_focus
function in mutter/src/wayland/meta-wayland-keyboard.c
acknowledges this limitation with a comment
* Since the use case for the pressed keys array on enter seems weak
* to us, we'll just fake that there are no pressed keys instead
* which should be spec compliant even if it might not be true.
Related task: #2231 (closed)