Word Export: prevent cross-thread exception

When disposing the ClerkActivator do not update the status bar
in the call to ActivateUI().
XHTML export is also calling this from a different thread but we
were not seeing this error because the text string was the same
as the current value so no change was made.
Notes:
In OnExport(), after the command completes, we call
ActivateUI() a second time, and this time we do update the
status bar.
The exception was only happening when there were reversals
and it seemed to only/mostly happen in debug builds.

Change-Id: Ife8957181e5a07736b1f56e2f488aa92c8f226c5

Src/xWorks/DictionaryExportService.cs

@@ -191,7 +191,7 @@ private void Dispose(bool disposing)
 			{
 				System.Diagnostics.Debug.WriteLineIf(!disposing, "****** Missing Dispose() call for " + GetType() + " ******");
 				if (disposing && m_currentClerk != null && !m_currentClerk.IsDisposed)
-					m_currentClerk.ActivateUI(true);
+					m_currentClerk.ActivateUI(true, false);
 			}
 
 			~ClerkActivator()