gdk:window-source-events (window source)

window -- a gdk:window object
source -- a gdk:input-source value to define the source class
event-mask -- a gdk:event-mask event mask for window

The gdk:window-source-events function returns the event mask for the window corresponding to the device class specified by source. The (setf gdk:window-source-events) function sets the event mask for any floating device, i.e. not attached to any visible pointer, that has 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.