Here's example code that highlights left and right pane of https://www.w3schools.com/css/tryit.asp?filename=trycss_buttons_basic which uses iframe.
function Panes()
{
var page = NameMapping.Sys.Browser("chrome").Page("https://www.w3schools.com/css/tryit.asp?filename=trycss_buttons_basic").Panel("container");
var left = page.Panel("textareacontainer").Panel("textarea").Panel("textareawrapper").Panel(0).Panel(5).Panel(0).Panel(0).Panel(0).Panel(0).Panel(4);
var right = page.Panel("iframecontainer").Panel("iframe").Panel("iframewrapper").Frame("iframeResult").Button("Input Button");
Sys.HighlightObject(left);
Sys.HighlightObject(right);
}