Bug 390177 - persisted thread pane size halved after adjust and restart, r=mscott

mail/base/content/messenger.xul

@@ -302,6 +302,7 @@
     <vbox flex="1">
       <box orient="vertical" id="messagesBox" flex="1">
           <deck id="displayDeck" flex="1" selectedIndex="0"
+                minheight="100" height="100" persist="height"
                 onselect="ObserveDisplayDeckChange(event)">
           <!-- first panel in displayDeck is Account Central -->
           <vbox id="accountCentralBox" flex="1">
@@ -309,7 +310,7 @@
           </vbox>
           <!-- second panel is the threadPane -->
           <hbox id="threadPaneBox">
-            <tree id="threadTree" persist="lastfoldersent" flex="2" enableColumnDrag="true" _selectDelay="500" class="plain focusring" lastfoldersent="false"
+            <tree id="threadTree" persist="lastfoldersent width" flex="2" enableColumnDrag="true" _selectDelay="500" class="plain focusring" lastfoldersent="false"
                          disableKeyNavigation="true"
                          context="threadPaneContext"
                          onkeypress="ThreadPaneKeyPress(event);"