[Gtk-sharp-list] Custom widgets

Sergio Rubio sergio.rubio@hispalinux.es
Tue, 17 Aug 2004 00:16:50 +0200

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I'm trying to make a custom widget derived form Gtk.ImageMenuItem.
When I click on the the widget I get the following exception:

Unhandled Exception: GLib.MissingIntPtrCtorException: GLib.Object
subclass Gtk.Ext.ActionMenuItem must provide a protected or public
IntPtr ctor to support wrapping of native object handles.

If I add the IntPtr constructor I get two constructor calls: one when
the custom widget object is created and the other one when the item is

public ActionMenuItem (UIAction action) : base (action.Label)
	// This is called when the object is created

public ActionMenuItem (IntPtr ptr) : base (ptr)
	// This is called when the user clicks the MenuItem

So it seems that two diferent instances of ActionMenuItem are created,
and if I use any local variables in the ActionMenuItem class a
System.NullReferenceException is thrown when I click on the menu item
because the second instance variables are not initialized.

The funny thing is that sometimes it works fine, I mean, it doesn't
throw the GLib.MissingIntPtrCtorException.

Am I missing something? What should I do to workaround this?. I
appreciate your help.


P.S.: The ActionMenuItem class is attached.


::: sergio.rubio@hispalinux.es :::
::: http://mspace.berlios.de   :::
::: rubiojr@jabber.org         :::

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 * Copyright (C) 2004 Sergio Rubio <sergio.rubio@hispalinux.es>
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * General Public License for more details.
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.

namespace Gtk.Ext {
    using Gtk;
    using System;
    public class ActionMenuItem : ImageMenuItem
	protected UIAction action;

	public ActionMenuItem (UIAction action) : base (action.Label)
	    this.action = action; 
	    Image img = new Image ();
	    img.SetFromStock(action.StockIcon, IconSize.Menu);
	    Image = img;
	    InitComponent ();

	private void InitComponent ()
	    action.IconSize = IconSize.Menu;
	    Sensitive = action.Enabled;
	protected override void OnActivated ()
	    base.OnActivated ();
	    if (!action.Enabled)
	    action.ActionPerformed ();