Differences between Gtk1 and Gtk2

[Marcos Leal <marcos polyflow com>]

I used to have some users parameters passed through 'gpointer user_data'
For example, the event for pressed button I used to declare in GTK1 like :
void on_button_pressed(GtkButton *button, gpointer user_data)

I don't even know if this is the right thing to do.

There's no 'gpointer user_data' on GTK2 anymore. But, is there any way 
to do the same thing ?

Best Regards
Marcos