title: Why not getting `ButtonPressEvent`
body: <p>I am experimenting a bit with monodevelop/c#/gdk and I was able to create a window with a <code>DrawingArea</code> correctly handling the expose event.</p>
  
  <p>The mouse down events however are not dispatched and I don't understand why. The delegates have been set up in the code autogenerated by the gui designer:</p>
  
  <pre><code>this.da.ExposeEvent += new global::Gtk.ExposeEventHandler (this.OnDAExposeEvent);
  this.da.ButtonPressEvent += new global::Gtk.ButtonPressEventHandler (this.OnDAButtonPressEvent);
  this.da.MotionNotifyEvent += new global::Gtk.MotionNotifyEventHandler (this.OnDAMotionNotifyEvent);
  </code></pre>
  
  <p>and this is my initialization code:</p>
  
  <pre><code>public MainWindow () : base (Gtk.WindowType.Toplevel)
      {
          Build ();
          Gdk.Color col = new Gdk.Color();
          col.Red = col.Green = col.Blue = 0x8888;
          da.ModifyBg(StateType.Normal, col);
          var p = "wr/wn/wb/wq/wk/wp/br/bn/bb/bq/bk/bp".Split ('/');
          for (int i = 0; i &lt; p.Length; i++) {
              pieces[p[i]] = new ImageSurface("/home/agriffini/x/chessboard/i" + p [i] + ".png");
          }
          da.Events |= (Gdk.EventMask.ButtonPressMask
                        | Gdk.EventMask.ButtonReleaseMask
                        | Gdk.EventMask.KeyPressMask
                        | Gdk.EventMask.PointerMotionMask);
      }
  </code></pre>
  
  <p>however the handler function <code>OnDAButtonPressEvent</code> never gets called (checked by placing a breakpoint there).</p>
  
  <p>What is the part that is missing?</p>