Under the buttons-and-menu interface, the change button in free-text searching screen contains an invalid action=$varbtnaction, i.e. template is not expanded.
In Template.pm, sub varbtnaction uses the existing fileref, diffref and idref subs to get a skeletal <a> link corresponding to scripts source, diff and ident respectively. Unhappily there is no such sub for search. varbtnaction generates directly the action, but the string then goes thru a pattern extraction to get the href target.
You should mock up a href also for search, otherwise the sub returns undef and the template $varbtnaction is left unchanged (not removed).