gtk_action_set_sensitive (de->insert_variable, TRUE);
gtk_action_set_sensitive (de->insert_case, FALSE);
gtk_action_set_sensitive (de->invoke_goto_dialog, FALSE);
break;
case PAGE_DATA_SHEET:
gtk_widget_show (view_variables);
gtk_action_set_sensitive (de->insert_variable, TRUE);
gtk_action_set_sensitive (de->insert_case, FALSE);
gtk_action_set_sensitive (de->invoke_goto_dialog, FALSE);
break;
case PAGE_DATA_SHEET:
gtk_widget_show (view_variables);