Re: [gtk-list] Trying to add widgets via callback

[Tim Janik <timj gimp org>]

On Mon, 23 Feb 1998, Toshio Kuratomi wrote:

> Hello.
> I'm trying to add widgets into a vbox when a user clicks on a button.
> Unfortunately, all I'm getting so far is SegV.  I've run the program
> through gdb and I think I'm having problems passing my vbox (pointer)
> into the callback, but I'm not sure of the remedy.
> If anyone could help me, I'd be most appreciative.
> 
> Here is the code I'm using:
> [][][][][][][][]
> 
> GtkHandleBox *
> newEntry (char *note) {
> 
>  GtkWidget *entry_area;
>  GtkWidget *container;
> 
>  container = gtk_handle_box_new();
>  entry_area = gtk_entry_new();
> 
>  gtk_container_add(GTK_CONTAINER(container),entry_area);
>  gtk_widget_show(entry_area);
> 
>  return GTK_HANDLE_BOX(container);
> }
> 
> void
> addEntry (GtkWidget widget,
>           GtkBox **container_to_add_to) {
		   ^^^^^^^^^^^^^^^^^^^^^^
		   should be *container_to_add_to
> 
>  GtkWidget *entry_box;
>  entry_box=newEntry(NULL);
> #if 0
> The next line is where I segV out.  At one point I was passing
> container_to_add_to in as a GtkWidget * and then the segV occurred
> in the casting function GTK_BOX(container_to_add_to)....
> #endif
>  gtk_box_pack_start(*container_to_add_to,entry_box,TRUE,TRUE,0);
		      ^^^^^^^^^^^^^^^^^^^^
		      should be (container_to_add_to)
>  gtk_widget_show(entry_box);
> 
> }
> 
> GtkWindow *
> newWindow (GtkHandleBox *initial_note) {
> 
> /* Define the basic necessities of a window. */
>  GtkWidget *top_window;
>  GtkWidget *vbox;
>  GtkWidget *new_entry_button;
> [snip]
> 
> /* Create the widgets that go into our program. */
>  top_window = gtk_window_new(GTK_WINDOW_TOPLEVEL);  // Create Managed window
>  vbox = gtk_vbox_new(FALSE,0);              // Create the layout box.
>  new_entry_button = gtk_button_new_with_label("New Entry");
> 
>  gtk_signal_connect(GTK_OBJECT(top_window), "delete_event",
>                     GTK_SIGNAL_FUNC(closeWindow), top_window);
> 
>  gtk_signal_connect(GTK_OBJECT(new_entry_button), "clicked",
>                     GTK_SIGNAL_FUNC(addEntry), &vbox);
						 ^^^^^
						 should be (vbox), since
vbox already is a pointer to your container, and the contents of
&vbox will be lost after newWindow is left because the it is a stack
variable.

> [snip]
> 
> [][][][][][][][]
> 
> -Toshio Kuratomi <badger@prtr-13.ucsc.edu>
> -- 

---
ciaoTJ