rem: messenger.OpenURL("about:blank");  
add: if (window.frames["messagepane"].location != "about:blank") window.frames["messagepane"].location = "about:blank" 
context: function ClearMessagePane(){	messenger.OpenURL("about:blank");	}
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/1e90278389eaee7d4e9b9fd2b5e3d7fd0a257c92/msgMail3PaneWindow.js/buggy/mailnews/base/resources/content/msgMail3PaneWindow.js