Label.setMarkup

Parses str which is marked up with the Pango text markup language, setting the label’s text and attribute list based on the parse results.

If the str is external data, you may need to escape it with glib.global.markupEscapeText or glib.global.markupPrintfEscaped:

GtkWidget *label = gtk_label_new (NULL);
const char *str = "some text";
const char *format = "<span style=\"italic\">\%s</span>";
char *markup;

markup = g_markup_printf_escaped (format, str);
gtk_label_set_markup (GTK_LABEL (label), markup);
g_free (markup);

This function will set the #GtkLabel:use-markup property to true as a side effect.

If you set the label contents using the #GtkLabel:label property you should also ensure that you set the #GtkLabel:use-markup property accordingly.

See also: gtk.label.Label.setText