g_list_remove problem

[Rob Clack <rnc sanger ac uk>]

Not sure this is really the right list for this question, but it 
overlaps two areas, so trying here first.  I've spent days on this, both 
hacking the code and searching the archives, without making any progress.

I have a window that the user can split as many times as she wants.  The 
repeating components, vpane, frame, scrolled_window, canvas, live in a 
structure I call a splitPane. To keep track of the panes, I use a GList, 
to which I g_list_append(panesList, splitPane).

When closing panes, it's all fine as long as the pane I'm closing is in 
the last element of the list.  The problem arises when closing a pane 
other than the last one.  I remove it from the GList with
list = g_list_remove(panesList, splitPane);
but after that all trailing elements in the list are broken.  The 
pointers look good, but any gtk reference to the actual objects yields 
gtk errors or seg faults.


Here is a code fragment:

      /* find the pane we want to close in the list */
      element = g_list_find(panesList, focuspane);

      /* remove it from the list */
      panesList = g_list_remove(panesList, focuspane);

      /* point at previous entry  or start of list if none */
      element = g_list_previous(panesList);
      if (!element)
        element = panesList;

      /* destroy the pane - should do frame, swindow, canvas, too */
      gtk_widget_destroy(focuspane->pane);

      /* focus on the appropriate pane */
      gtk_widget_grab_focus(((splitPane*)element->data)->pane);


(split:7604): Gtk-CRITICAL **: file gtkwidget.c: line 3400 
(gtk_widget_grab_focus): assertion `GTK_IS_WIDGET (widget)' failed

There must be something simple I'm doing wrong but I can't see it.  Hope 
someone else can.

Thanks
Rob
--
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Junk is something you've kept for years and then throw away three weeks
 before you need it.
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Rob Clack                        Acedb Development,  Informatics Group
 email: rnc sanger ac uk                Wellcome Trust Sanger Institute
 Tel: +44 1223 494883                   Wellcome Trust Genome Campus
 Fax: +44 1223 494919                   Hinxton  Cambridge    CB10 1SA