add: document.getElementById("daysEnd").disabled = locked || !leaveMsgsChecked; 
context: function setupAgeMsgOnServerUI(){    var leaveMsgsChecked = document.getElementById("pop3.leaveMessagesOnServer").checked;   var checked = document.getElementById("pop3.deleteByAgeFromServer").checked;   var locked = getAccountValueIsLocked(document.getElementById("pop3.deleteByAgeFromServer"));   document.getElementById("pop3.deleteByAgeFromServer").disabled = locked || !leaveMsgsChecked;   document.getElementById("pop3.numDaysToLeaveOnServer").disabled = locked || !checked || !leaveMsgsChecked;}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/8ad7dde5c6244e2bebb0c6615887f6329c3f0ad9/am-server.js/clean/mailnews/base/prefs/resources/content/am-server.js