backing out my fix for 200603, and neils supplimental fix for it.

mailnews/compose/resources/content/messengercompose.xul

@@ -440,7 +440,6 @@
             <menulist id="msgIdentity" label="..." flex="1" oncommand="LoadIdentity(false);">
               <menupopup id="msgIdentityPopup"/>
             </menulist>
-            <spacer flex="1000"/>
           </hbox> 
           <listbox id="addressingWidget" flex="1"/>
           <hbox align="center">