rem: EnableMenuItem("folderPaneContext-compact", true ); 
add: var folder = GetMsgFolderFromNode(targetFolder); EnableMenuItem("folderPaneContext-compact", folder.isCommandEnabled("cmd_compactFolder")); 
context: function SetupCompactMenuItem(targetFolder, numSelected){    var canCompact = (targetFolder.getAttribute('CanCompact') == "true");  ShowMenuItem("folderPaneContext-compact", (numSelected <=1) && canCompact);  EnableMenuItem("folderPaneContext-compact", true );  if(canCompact)  {    SetMenuItemLabel("folderPaneContext-compact", gMessengerBundle.getString("compactFolder"));  }}
meta: 9421	/local1/tlutelli/issta_data/temp/all_js/javascript/2006_temp/2006/9421/ce4cd2a55aca78a79ddf0a21a73d6c1c077fdae1/mailContextMenus.js/clean/mailnews/base/resources/content/mailContextMenus.js