<div id="t" style="height: 100px; overflow: hidden;">
    <br><br><br><br>
    Should have blue, not gray, highlight<br>
    <br><br><br><br>
</div>
<script>
    var t = document.getElementById("t");
    getSelection().setBaseAndExtent(t, 5, t, 6);
    t.scrollTop = 100;
</script>