rem: window.frames["messagepane"].location = "about:blank" 
add: window.frames["messagepane"].location = "about:blank";  HideMessageHeaderPane(); 
context: function ClearMessagePane(){    if (window.frames["messagepane"].location != "about:blank")        window.frames["messagepane"].location = "about:blank"}
meta: 8395	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/8395/cc713cbb1440a32dccb2b578cd98616ad1df9bcb/msgMail3PaneWindow.js/clean/mailnews/base/resources/content/msgMail3PaneWindow.js