Refuses to function if this difference has been edited, i.e., if it is
neither the A nor the B variant.
An argument forces the variant to be selected even if the difference has
-been edited."
- (interactive "cRegister containing template: \nP")
+been edited.
+
+Interactively, reads the register using `register-read-with-preview'."
+ (interactive (list
+ (register-read-with-preview "Register containing template: ")
+ current-prefix-arg))
(let ((template (get-register char)))
(if (not (stringp template))
(error "Register does not contain text"))