gtk_widget_set_sensitive(back_btn, FALSE);
void on_split_clicked(GtkButton * button, gpointer user_data){	gint w, h;	view_mode = SPLIT_VIEW;	gtk_widget_show(tree1_w);	gtk_window_get_default_size(GTK_WINDOW(main_wnd), &w, &h);	gtk_paned_set_position(GTK_PANED(hpaned), w / 2);	if (tree2)			gtk_tree_store_clear(tree2);	display_list();}