Writing C++ apps with Gtk?

[Lars Hoss <lars hoss munich netsurf de>]

Hi,

I am working on a C++ Gtk application.
Now I have a strange prob with the callback functions.
The pointer to the widget in the callback function seems to be
somewhat incorrect?

Here's a simple example:

#include <stdio.h>
#include "toplevel.h"

TopLevel::TopLevel()
{
  GtkWidget *window;
  GtkWidget *button;
  
  window = gtk_window_new( GTK_WINDOW_TOPLEVEL );
  gtk_container_border_width( GTK_CONTAINER(window), 10 );

  button = gtk_button_new_with_label( "C++ Test" );
  gtk_signal_connect( GTK_OBJECT(window), "destroy",
                      GTK_SIGNAL_FUNC(TopLevel::cbDestroy), this );
  gtk_signal_connect( GTK_OBJECT(button), "clicked",
                      GTK_SIGNAL_FUNC(TopLevel::cbHello), this );

  gtk_container_add( GTK_CONTAINER(window), button );
  
  gtk_widget_show(button);
  gtk_widget_show(window);
}

void TopLevel::run()
{
  gtk_main();
}

void TopLevel::cbHello( GtkWidget *widget, gpointer data )
{
  g_print( "width:%d height:%d\n", 
           widget->allocation.width, 
           widget->allocation.height );
}

void TopLevel::cbDestroy( GtkWidget *widget, gpointer data )
{
  printf( "DEBUG: called cbDestroy!\n" );
  gtk_main_quit();
}

The function TopLevel::cbHello is important.
This width and height aren't the correct values, so the pointer
must be wrong?
How can I fix this?

Thanx for your help,
Lars

-- 
Lars Hoss
email: Lars.Hoss@munich.netsurf.de
WWW: http://www.informatik.uni-muenchen.de/~hoss