How do I select / highlight all text in AW.Templates.Input?

How do I select all text in AW.Templates.Input? In a plain HTML INPUT Form, I can do the following:

<input name="username" type="text" id="username" value="Copy of demouser1">

<script>
function highlight(field) {
field.focus();
field.select();
}
highlight(document.myform.username);
</script>

Thanks in advnace,
Michael

this works

this works