Vala GTK+. Issue with customized widget - events

Question

I need to create a gtk.Entry which accepts only numbers. but I can't overwrite the key_press_event event in an heredited class. It only works if I use the original Entry by means of connect function.
What am I doing wrong?
using Gtk;
public class NumberEntry : Entry {
public void NumberEntry(){
add_events (Gdk.EventMask.KEY_PRESS_MASK);
}
//With customized event left entry editing is not possible
public override bool key_press_event (Gdk.EventKey event) {
string numbers = "0123456789.";
if (numbers.contains(event.str)){
return false;
} else {
return true;
}
}
}
public class Application : Window {
public Application () {
// Window
this.title = "Entry Issue";
this.window_position = Gtk.WindowPosition.CENTER;
this.destroy.connect (Gtk.main_quit);
this.set_default_size (350, 70);
Grid grid = new Grid();
grid.set_row_spacing(8);
grid.set_column_spacing(8);
Label label_1 = new Label ("Customized Entry, useless:");
grid.attach (label_1,0,0,1,1);
//Customized Entry:
NumberEntry numberEntry = new NumberEntry ();
grid.attach(numberEntry, 1, 0, 1, 1);
Label label_2 = new Label ("Working only numbers Entry:");
grid.attach (label_2,0,1,1,1);
//Normal Entry
Entry entry = new Entry();
grid.attach(entry, 1, 1, 1, 1);
this.add(grid);
//With normal Entry this event works well:
entry.key_press_event.connect ((event) => {
string numbers = "0123456789.";
if (numbers.contains(event.str)){
return false;
} else {
return true;
}
});
}
}
public static int main (string[] args) {
Gtk.init (ref args);
Application app = new Application ();
app.show_all ();
Gtk.main ();
return 0;
}

Answer 1

The key_press_event of the superclass is no longer being called. You need to call the base class and return true when you have consumed the key.
public override bool key_press_event (Gdk.EventKey event) {
string numbers = "0123456789.";
if (numbers.contains(event.str)){
return base.key_press_event (event);
} else {
return true;
}
}
If you return false in a signal, this can be passed to an alternate handler, but only if you use connect and not override the signal method.