If a file in the srcdir is removed, exposing a file in the underlaydir,
-ikiwiki will not notice the change and rebuild it until the file in the
-underlaydir gets a mtime newer than the mtime the removed file had.
+ikiwiki will not notice the removal, and the
+page from the underlay will not be built. (However, it will be if the wiki
+gets rebuilt.)
+
+> This problem is caused by ikiwiki storing only filenames relative to
+> the srcdir or underlay, and mtime comparison not handling this case.
+
+> A related problem occurs if changing a site's theme with the
+> [[plugins/theme]] plugin. The style.css of the old and new theme
+> often has the same mtime, so ikiwiki does not update it w/o a rebuild.
+> This is worked around in theme.pm with a special-purpose needsbuild hook.
+> --[[Joey]]