add: document.getElementById("key_toggleMessagePane").removeAttribute("disabled"); 
context: function ShowingThreadPane(){  var threadPaneSplitter = document.getElementById("threadpane-splitter");  threadPaneSplitter.collapsed = false;  GetMessagePane().collapsed = (threadPaneSplitter.getAttribute("state") == "collapsed");}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/e29db857d189867d3ded0ecde46ba40049e5b40c/mailWindow.js/clean/mail/base/content/mailWindow.js