This patch fixes some bugs and adds new features to the GtkNotebook widget.
The patch is against gtk+-0.99.3.

[FIX] (gtk_notebook_size_request) :
   container border width > 0 doesn't work correctly in case of "show_tabs"

[FIX] (gtk_notebook_pages_allocate) :
   container border width > 0 doesn't work correctly in case of 
   GTK_POS_BOTTOM / GTK_POS_RIGHT

[FIX] (gtk_notebook_page_allocate) :
   the tab label is sized too big (by CHILD_SPACING)
   e.g. GTK_POS_TOP : 
      tab_label->allocation.height was
      tab_label->requisition.height + CHILD_SPACING

[FIX] (gtk_notebook_show_tabs) :
    tab labels were not hidden/shown when toggling "show_tabs"

[FIX] (gtk_notebook_remove_page) :
    call gtk_notebook_switch_page if "cur_page" is removed

[CHANGE] (gtk_notebook_next_page / prev_page) :
    use g_list_find instead of while loop (which was never "break"ed)

[CHANGE] :
    globally replaced "GTK_WIDGET (widget)->style->..."
    with "widget->style->..."

[ADDED] :
    Scrollable tab section. Can be toggled with gtk_notebook_set_scrollable.

[ADDED] :
    focus handling / keyboard handling

[CHANGE] :
    testgtk was changed accordingly