There are a couple of issues here.

The first is that some GTK+ widgets do not by nature receive events of any nature - GtkLabel comes to mind as an example. (The technical reason behind this is that they do not have their own X window, but use the one belonging to their parent widget. An X window is not the same as a GTK+ window, mind you; X windows on Unix systems are wrapped by GDK's GdkWindow, which is a lower-level creature). These widgets are listed at [www.moeraki.com] , and discussed further in gtkmm's tutorial: [www.gtkmm.org] . If you want to receive events for one of these widgets, you should add a GtkEventBox around it, and listen for events on that box.

 l = gtk.Label("I want events.")
 e = gtk.EventBox()
 e.add(l)
 e.add_events(gtk.gdk.POINTER_MOTION_MASK)
 e.connect("motion-notify-event", handle_event)

Additionally, to receive signals, the widget's event mask must be set accordingly. In the answer to FAQ 3.2, for instance, we had to adjust it to receive pointer motion events (among others) - if we didn't, motion_notify_event would never be emitted.

The event masks are defined in the gdk module; they are constants whose name ends in "_MASK". They map directly to X11 masks, and there is a reference to what each X11 mask is at [tronche.com]

The functions that adjust the masks are:

 widget.set_events() 

and

 widget.add_events()

the second one only adding to the widgets mask, the first one in effect replacing the original mask (* though I believe the "factory supplied" mask is not replaced, but added to, even in the case of set_events()).

In the specific case of the key_press_event, the GTK+ event queue treats this signal specially to manage the widget keyboard focus.When it sees key events targetted at any subwindow within the toplevel, they are redirected to the toplevel GtkWindow. The key_press_event handler for the toplevel window checks to see if the key event corresponds to an accelerator/mnemonic (and activates the appropriate widget if so), or passes the key event on to the widget with focus. In short: if you want a global keyhandler, attach it to your application's GtkWindow(s).

Finally, understanding how the signal propagation system works is also helpful when you run into a tricky situation - you should check out FAQ 3.11 which has more information on this.