The "clicked" signal is emitted at the midpoint between pressing and releasing the mouse-button. This is the most commonly used GtkButton signal, and holds an advantage over the other signals listed here in that it also responds to enter or spacebar keypresses as though they were mouse-clicks. Signals that have this property are wrappers for an internal GtkWidget signal named 'activate_signal'; all interactive widgets contain one such method/signal pair, with appropriate keyboard bindings.

Note that the "clicked" signal will not fire when the mouse-button is released after the cursor has left the widget's region. The activate type of signals are by nature region-specific.

Use one of the connect() methods in order to emit the signal and connect it to your function. The connected function is known as the callback or signal-handler function:

<?php

dl('php_gtk.' . (strstr(PHP_OS, 'WIN') ? 'dll' : 'so'));

function my_function() {
  echo "The button was clicked\n";
}

$window = &new GtkWindow();
$window->set_position(GTK_WIN_POS_MOUSE);
$window->connect_object('destroy', array('gtk', 'main_quit'));

$button = &new GtkButton("Click Me");
$button->connect('clicked', 'my_function');
$window->add($button);

$window->show_all();

gtk::main();

?>

Callback function