Esta bien que nos miremos el manual: mira este codigo lo pone en el manual esplicado.
Código PHP:
<?php
dl('php_gtk.'.(strstr(PHP_OS, 'WIN') ? 'dll' : 'so'));
$window = &new GtkWindow();
$window->set_position(GTK_WIN_POS_CENTER);
$window->connect_object('destroy', array('gtk', 'main_quit'));
$box = &new GtkHBox();
$window->add($box);
$text = &new GtkText();
$text->set_word_wrap(true);
$string = "This is a string of text which will be displayed in the
GtkText widget.\n\nIt isn't long enough to allow scrolling, so you
will probably need to extend it.\n\nOn the other hand, the box
isn't sized, so it may just creep over that limit and be a useful
demonstration after all.";
if(strstr(PHP_OS, 'WIN'))
$string = wordwrap($string, 26);
$text->insert_text($string, 0);
$box->pack_start($text);
$adj = $text->vadj;
$scrollbar = &new GtkVScrollbar($adj);
$box->pack_end($scrollbar, false);
$window->show_all();
gtk::main();
?>