Last modified: 2012-03-20 17:25:36 UTC
When $wgReadOnly is not empty, database is locked. When user tries to edit a page, s/he receives a warning: You will not be able yo save the page, because... However, when editing a page through a form, there is no any warnings. It will be error when user saves the page. But it would be great to have such a warning in advance.
Thanks for the bug report; I believe I just fixed this in SVN.