Getting error message:
Notice: Undefined variable: highlighted in include() (line 56 of [...]/sites/all/themes/zen/templates/maintenance-page.tpl.php)
where [...] is the upper directory structure of my site's location.
This warning pops up in red at /user/login when the "default theme" is my own subtheme, but not when the "default theme" is Zen itself.
Sure enough, maintenance-page.tpl.php does have as line 56 "
&#lt;?php print $highlighted; ?&#gt;.
My sub-theme doesn't include a replacement maintenance-page.tpl.php. But I wonder if in writing the sub-theme I've changed something else which has hindered it from setting the variable.
I don't think I've done anything non-kosher, so I'd have expected such a thing to degrade gracefully, in which case this would count as a bug (which is what I've provisionally set it to). But I'm happy to receive feedback/questions along the lines of "Did you change the XYZ? because that's probably what broke it" :-)