add: var folderURI = GetSelectedFolderURI(); var server = GetServer(folderURI); if (!(server.canCompactFoldersOnServer)) return false;  
context: function IsCompactFolderEnabled(){    var folderOutliner = GetFolderOutliner();    var startIndex = {};    var endIndex = {};    folderOutliner.outlinerBoxObject.selection.getRangeAt(0, startIndex, endIndex);    if (startIndex.value < 0)         return false;    var folderResource = GetFolderResource(folderOutliner, startIndex.value);    if (! folderResource)         return false;    return GetFolderAttribute(folderOutliner, folderResource, "CanCompact") == "true" && isCommandEnabled("cmd_compactFolder");}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/0d80ab9fb5505377f232b90eee1ec27d04223fc1/mailWindowOverlay.js/buggy/mailnews/base/resources/content/mailWindowOverlay.js