gistfile1.js

var mozmill = {}; Components.utils.import('resource://mozmill/modules/mozmill.js', mozmill);
var elementslib = {}; Components.utils.import('resource://mozmill/modules/elementslib.js', elementslib);


var testFoo = function(){
  var controller = mozmill.getMail3PaneController();
  var e = 
new elementslib.XPath(controller.window.frames[0].document, "/*[name()='page' and namespace-uri()='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul']/*[name()='grid' and namespace-uri()='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul'][1]/*[name()='rows' and namespace-uri()='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul'][1]/*[name()='row' and namespace-uri()='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul'][16]/*[name()='hbox' and namespace-uri()='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul'][1]/*[name()='label' and namespace-uri()='http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul'][1]");

  controller.click(e);
}