GTK+3 motion events and is_hint

[Donn <donn ingle gmail com>]

Hi,
(Like in idiot I sent the first version of this to the wrong list!)


Hi, I'm new to GTK (and Vala). This is a Gtk+3.x question.

Can anyone explain why the event->is_hint always seems to return 1?
AFAICT the HINT_MASK is supposed to reduce the number of motion events 
*and* send the occasional is_hint==true too.

ref: https://developer.gnome.org/gdk3/stable/gdk3-Events.html#GdkEventMask



I include a small vala sample at end. The motion_notify_event handler 
never gets the chance to follow the else. i.e.

Am I grokking this wrong, or making a stupid mistake or .. other?


--
//valac --pkg gtk+-3.0 appname.vala

using Cairo;

namespace Demo {

public class Scribble : Gtk.DrawingArea {

  public Scribble () {
    this.add_events ( Gdk.EventMask.POINTER_MOTION_MASK | 
Gdk.EventMask.POINTER_MOTION_HINT_MASK );
    this.set_size_request (100,100);
  }

  private void draw_circ ( Cairo.Context cr ) {
      var y = get_allocated_height () / 2;
      var radius = double.min (get_allocated_width () / 2, 
get_allocated_height () / 2) - 5;
      cr.arc (y, y, radius, 0, 2 * Math.PI);
      cr.set_source_rgb (1, 1, 1);
      cr.fill_preserve ();
      cr.set_source_rgb (0, 0, 0);
      cr.stroke ();
  }

  public override bool draw ( Cairo.Context cr ) {
      this.draw_circ ( cr);
      return false;
  }

  public override bool motion_notify_event (Gdk.EventMotion event ) {
    //Seems event.is_hint is *always* 1
    //stdout.printf ( "is_hint: %d\n", event.is_hint );

    if (event.is_hint == 1) {
      stdout.printf ( "is hint\n" );
      Gdk.Event.request_motions(event); //Always 1, so what's the point?
    } else {
      //Never gets here. Why?
      stdout.printf ( "normal motion at: %G, %G\n", event.x, event.y );
    }
    return true; //false does not change anything either.
  }

}
}

int main ( string[] args ) {
  Gtk.init ( ref args );
  var window = new Gtk.Window ();
  var scribble = new Demo.Scribble ();

  window.add (scribble);
  window.show_all ();
  window.destroy.connect (Gtk.main_quit);

  Gtk.main ();

  return 0;
}


--


PS - I have since asked this on Stackoverflow.
The url is:

http://stackoverflow.com/questions/16359775/gtk-motion-notify-event-is-hint-always-true


Thanks,
\d