gtk:text-buffer-register-serialize-format (buffer mime func)

buffer -- a gtk:text-buffer object
mime -- a string with the MIME type of the format
func -- a gtk:text-buffer-serialize-func serialize function to register

The gdk:atom as a string that corresponds to the newly registered MIME type of the format.

This function registers a rich text serialization function along with its MIME type with the passed text buffer.