gtkD mouse press event on Notebook

    private import std.stdio;
    private import gtk.Main;
    private import gtk.MainWindow;
    private import gtk.Label;
    private import gtk.Notebook;
    private import gtk.Widget;
    private import gdk.Event;

    class mdinWindow : MainWindow
    {
            this ()
            {
                    super ( " " );
                    Notebook nb = new Notebook;

                    Label lbl = new Label ( "Tab1" );
                    nb . appendPage ( lbl, new Label ( "a" ) );
                    nb . setTabReorderable ( lbl, true );

                    Label lbl2 = new Label ( "Tab2" );
                    nb . appendPage ( lbl2, new Label ( "Page2" ) );
                    nb . setTabReorderable ( lbl2, true );

                    //nb . addOnButtonPress ( &mousepressevent );
                    add ( nb );
                    showAll ();
            }
            bool mousepressevent ( Event ev, Widget w )
            {
                    uint bt;
                    ev . getButton ( bt );
                    if ( bt == 1 )
                    {
                            double x, y;
                            ev . getRootCoords ( x, y );
                            beginMoveDrag ( cast ( int ) bt, cast ( int ) x, cast ( int ) y, ev . getTime () );
                    }
                    return false;
            }
    }

    void main ( string [] args )
    {
            Main . initMultiThread ( args );
            new mainWindow ();
            Main . run ();
    }