:format strings in Custom ending in %h

[Luc Teirlinck <teirllm@dms.auburn.edu>]

Is it a rule that :format strings are not allowed to end in %h?
If so where is this mentioned in either the Elisp manual or the
(widget) documentation?

Such format strings produce trouble as described below.

Do:

emacs-21.3.50 -q --eval "(blink-cursor-mode 0)" &

and load the following file:

===File ~/customdoc.el======================================
(defgroup nifty nil
  "Single item group"
  :group 'convenience)

(defcustom nifty-var nil
  "*Nifty doc string."
  :group 'nifty-group
  :type '(choice (const :tag "True"
			:format "%t\n%h"
			:doc
			"True stuff.
Second line of true stuff."
			t)
		 (other :tag "False"
			:format "%t\n%h"
			:doc
			"Falsehoods.
Second line of falsehoods"
			nil)))

============================================================

Then do:

M-x customize-group RET nifty

Click on "More" next to "Falsehoods."

Then click on "Value Menu" and choose "True".

Now we have:

True stuff. More
Falsehoods. Hide Rest
Second line of falsehoods
 
We should not have those last two lines any more and if we add a space
to both :format strings, i.e :format "%t\n%h ", and repeat the
exercise, they indeed disappear and everything works wonderfully.

Sincerely,

Luc.