Gtk.DrawingArea mouse events using Vala - mouseevent

Question

I have been trying to receive mouse events on my Gtk.DrawingArea, using Vala, with no success. Specifically I am sub-classing Gtk.DrawingArea and in my constructor I add the events I want to receive:
this.add_events (Gdk.EventMask.ENTER_NOTIFY_MASK |
Gdk.EventMask.BUTTON_PRESS_MASK);
Then, in the same constructor below, I register signal handlers for these events:
this.enter_notify_event.connect (
(page, event) => {
stdout.printf("mouse entered !!! \n");
return true;
}
);
this.button_press_event.connect (
(page, event) => {
stdout.printf("mouse click \n");
return false;
}
);
I tried both return true and return false to check what happens in both cases. However I see no messages on the console when I move the pointer on the Gtk.DrawingArea or when I click on it. I even set the events for the top Gtk.Window:
this.set_events (this.get_events() |
Gdk.EventMask.ENTER_NOTIFY_MASK |
Gdk.EventMask.BUTTON_PRESS_MASK);
but the events don't seem to get received. What could be going wrong?

Answer 1

Your code seems correct although it's not a MVCE. I would point out the callback handlers prototype as being incorrect but since you're not using event data it should not be a "problem". The callback prototypes for enter_notify_event and button_press_eventonly supply the event, so the page argument it's incorrect.
Anyway, i tested with a very simple and raw code and it worked. Please verify:
using Gtk;
public class MyWidget : Gtk.DrawingArea {
public MyWidget () {
this.set_events (Gdk.EventMask.ENTER_NOTIFY_MASK |
Gdk.EventMask.BUTTON_PRESS_MASK);
this.enter_notify_event.connect ((event) => {
stdout.printf ("mouse entered !!! \n");
return false;
});
this.button_press_event.connect ((event) => {
stdout.printf("mouse click \n");
return false;
});
}
}
public void main (string[] args) {
Gtk.init (ref args);
var window = new Gtk.Window ();
window.add (new MyWidget ());
window.destroy.connect (Gtk.main_quit);
window.show_all ();
Gtk.main ();
}
Compile with valac test.vala --pgk gtk+-3.0.
The result is:
Using Vala 0.30.2 and Gtk+ 3.18 on Fedora 23.