Sets the function to call to handle all events from GDK.
Note that GTK+ uses this to install its own event handler, so it is usually not useful for GTK+ applications. (Although an application
can call this function then call gtk_main_do_event to pass events to GTK+.)
| func |
the function to call to handle events from GDK. |
| data |
user data to pass to the function. |
| notify |
the function to call when the handler function is removed, i.e. when event_handler_set is called with another event handler. |