adapted clist pixmap clipping

adapted clist pixmap clipping

        * gtk/gtkctree.c (draw_row): adapted clist pixmap clipping

        * gtk/gtknotebook.h (struct _GtkNotebookClass):
        * gtk/gtknotebook.c (gtk_real_notebook_switch_page):
        added missing argument (according to Joseph Coleman's bug report)

        * gtk/gtknotebook.c (gtk_notebook_set_focus_child): new class
        function to fix notebook focus handling