disable unimplemented buttons, add hardrule above ok/cancel

mailnews/base/prefs/resources/content/AccountManager.xul

@@ -66,10 +66,10 @@
 	</tree>
 </html:div>
             <titledbutton value="&newAccountButton.label;" onclick="onNewAccount();"/>
-            <titledbutton value="&setDefaultButton.label;" onclick="document.getElementById('mydeck').setAttribute('value','2');"/>
+            <titledbutton value="&setDefaultButton.label;" disabled="true"/>
             <box align="horizontal">
-              <titledbutton value="&duplicateButton.label;" flex="50%"/>
+              <titledbutton disabled="true" value="&duplicateButton.label;" flex="50%"/>
-              <titledbutton value="&deleteButton.label;" flex="50%"/>
+              <titledbutton disabled="true" value="&deleteButton.label;" flex="50%"/>
             </box>
 		</box>
         <box flex="75%">