Checking in attachment 137260 with minor modification.

See bug 219589

calendar/resources/content/calendar.js

@@ -138,9 +138,6 @@ logMessage("application : " + applicationName);
 
 function calendarInit() 
 {
-  if(applicationName == "Thunderbird") {
-    document.getElementById( 'tasksMenuNavigator' ).setAttribute( "collapsed", "true" );
-   }
 	// get the calendar event data source
    gEventSource = new CalendarEventDataSource();
    
@@ -1033,7 +1030,7 @@ function goFindNewCalendars()
 
 function displayCalendarVersion()
 {
-   window.openDialog( getBrowserURL(), "_blank", "chrome,all,dialog=no", 'chrome://calendar/content/about.html' );
+   window.openDialog('chrome://calendar/content/about.xul', 'About','modal,centerscreen,chrome,width=500,resizable=yes');
 }
 
 function playSound( ThisURL )

calendar/resources/content/menuOverlay.xul

@@ -301,9 +301,7 @@
          <menuitem id="calendar-about-menu-item"
                    label="&calendar.about.label;"
                    accesskey="&calendar.about.accesskey;"
-                   oncommand="window.openDialog('chrome://calendar/content/about.xul',
-		                                'About',
-						'modal,centerscreen,chrome,width=500,resizable=yes');"/>
+                   oncommand="displayCalendarVersion();"/>
       </menupopup>
    </menu>      
 </menubar>