I've found another site that won't put the information into the log-in box,
www.catalogchoice.org. (I don't know that this can be considered a bug, but as I like to pester the PWM folks, I'm posting it here, more for their consternation than for any expected resolution of the problem.)
I suspect I know why, for here is the text from the page that brings up the log-in dialog:
<li>Already a member?</li>
<li><a class="highlight login" href="#" onclick="RedBox.createContainer('hidden_content_login'); ; new Ajax.Updater('hidden_content_login', '/login', {asynchronous:true, evalScripts:true, method:'get', onComplete:function(request){RedBox.addHiddenContent('hidden_content_login'); }, onLoading:function(request){RedBox.loading('hidden_content_login'); }}); return false;"><span>Log in</span></a></li>
When you click on "login", the main page goes dim, and a floating box appears in the center of the screen, asking for your log-in information. The "golden key" works fine, but not automatic population of the box when set to do so in PWM