Issue 2816 - Restore Preview functionality

chrome/content/composer.xul

Index: chrome/content/composer.xul
===================================================================
--- a/chrome/content/composer.xul
+++ b/chrome/content/composer.xul
@@ -7,33 +7,33 @@
 <!DOCTYPE overlay SYSTEM "chrome://elemhidehelper/locale/composer.dtd">
 
 <?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
 <?xml-stylesheet href="chrome://elemhidehelper/skin/composer.css" type="text/css"?>
 
 <dialog id="ehh-composer"
     xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
     title="&dialog.title;"
-    onload="init()"
+    onload="init();"
     ondialogaccept="addExpression();"
     ondialogdisclosure="setAdvancedMode(!advancedMode);"
-    onunload="togglePreview(false);"
+    onunload="togglePreview(false, true);"
     buttons="accept,cancel,disclosure"
     width="600px"
     height="400px"
     persist="screenX screenY width height sizemode advancedMode"
     advancedMode="false"
     buttonlabelaccept="&accept.label;"
     buttonlabeldisclosure="&advanced.label;"
     buttonlabeldisclosure_on="&advanced.label;"
     buttonlabeldisclosure_off="&basic.label;"
     windowtype="ehh:composer">
   <script type="application/x-javascript;version=1.7" src="common.js"/>
   <script type="application/x-javascript;version=1.7" src="composer.js"/>
-  
+
   <description id="groupDisabledWarning" hidden="true">&groupDisabled.warning;</description>
 
   <vbox id="expressionBox">
     <label control="expression" value="&expression.label;"/>
     <hbox>
       <textbox id="expression" flex="1" readonly="true"/>
       <checkbox id="preview" label="&preview.label;" checked="true" oncommand="togglePreview(this.checked)" persist="checked"/>
     </hbox>