syntax:
object insert(string what); OR
object insert(string what, GDK.Font font, GDK.Color fg, GDK.Color bg); OR
object insert(string what, 0, GDK.Color fg, GDK.Color bg); OR
object insert(string what, 0, GDK.Color fg); OR
object insert(string what, 0, 0, GDK.Color bg);
Insert new text, optionally with colors.