add: startPage.setElementValue(document.getElementById("mailnewsStartPageUrl")); 
context:   restoreDefaultStartPage: function()  {    var startPage = document.getElementById("mailnews.start_page.url");    startPage.value = startPage.defaultValue;  },
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/9421/c975cc257fa2d8cf1932e1e1c51c7513c4611fd5/general.js/clean/mail/components/preferences/general.js