public static uint add_filter (Stage? stage, owned EventFilterFunc func)
Adds a function which will be called for all events that Clutter processes.
The function will be called before any signals are emitted for the event and it will take precedence over any grabs.
The Stage to capture events for
The callback function which will be passed all events.
A data pointer to pass to the function.
an identifier for the event filter, to be used with remove_filter.