(defcustom gnus-build-sparse-threads nil
"If non-nil, fill in the gaps in threads.
-If `some', only fill in the gaps that are needed to tie loose threads
-together. If `more', fill in all leaf nodes that Gnus can find. If
-non-nil and non-`some', fill in all gaps that Gnus manages to guess."
+If set to the symbol `some', only fill in the gaps that are
+needed to tie loose threads together. If the symbol `more', fill
+in all leaf nodes that Gnus can find. If t (or any other value),
+fill in all gaps that Gnus manages to guess."
:group 'gnus-thread
:type '(choice (const :tag "off" nil)
(const some)