set_justify() is the method for justifying text in GtkLabel. The options are GtkJustification enumerated flags, the default setting being GTK_JUSTIFY_CENTER.

Justification is relative to existing lines of text, and should be used in combination with set_line_wrap() . It is irrelevant where there is only one line. If you need to set the text alignment in a single-line label, use set_alignment() . There is a working example of this method on the constructor page.

<?php

$label->set_line_wrap(true);
$label->set_justify(GTK_JUSTIFY_FILL);

?>