Create an editor
object from the specified arguments. If no text_buffer is specified, a
default empty text_buffer
object is used. The width and height arguments are interpreted in terms
of character units.
The margin specifies the with of the text_margin
object attached to the right side used for annotations. The default is
0, attaching no annotation margin. See also editor->margin.
Class view
encapsulates an editor
object in a window.