186081 patch by pratik psolanki@netscape.net r=smontagu sr=roc+moz printing doesn't work after print previewing a mail

mailnews/base/resources/content/msgPrintEngine.js

@@ -73,6 +73,8 @@ function showPrintPreviewToolbar()
 
 function BrowserExitPrintPreview()
 {
+  var webBrowserPrint = printEngine.webBrowserPrint;
+  webBrowserPrint.exitPrintPreview(); 
   window.close();
 }