Sets the event mask for any floating device (i.e. not attached to any
visible pointer) that has the source defined as @source. This event
mask will be applied both to currently existing, newly added devices
after this call, and devices being attached/detached.
Sets the event mask for any floating device (i.e. not attached to any visible pointer) that has the source defined as @source. This event mask will be applied both to currently existing, newly added devices after this call, and devices being attached/detached.