rem: viewPicker.selectedItem = document.getElementById(id); viewChange(viewPicker, viewPicker.value); 
add: if (viewPicker) { viewPicker.selectedItem = document.getElementById(id); viewChange(viewPicker, viewPicker.value); } 
context: function ViewMessagesBy(id){  var viewPicker = document.getElementById('viewPicker');  viewPicker.selectedItem = document.getElementById(id);  viewChange(viewPicker, viewPicker.value);}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/13c860b7e50f196af429dda9b5a1e9ceab991a5b/mailWindowOverlay.js/buggy/mail/base/content/mailWindowOverlay.js