Gtk.Label:width-chars
"width-chars" Number : Read / Write
The desired width of the label, in characters. If this property is set to -1, the width will be calculated automatically.
See the section on <link linkend="label-text-layout">text layout</link> for details of how Gtk.Label:width-chars and Gtk.Label:max-width-chars determine the width of ellipsized and wrapped labels.
Since 2.6