code: function closeContentAreaContextMenu(controller) {
    var contextMenu = new elementslib.ID(controller.window.document, "contentAreaContextMenu");
    controller.keypress(contextMenu, "VK_ESCAPE", {});
  }
docs: Close the context menu inside the content area of the currently open tab
  
  @param {MozmillController} controller
  MozMillController of the window to operate on