<p>This tests for a bug where centering two paragraphs would center the third.  Only the selected paragraphs should be selected.</p>
<div id="div" contenteditable="true">foo<div>bar<br>baz</div>

<script>
if (window.internals)
    internals.settings.setEditingBehavior('mac');
var div = document.getElementById("div");
var sel = window.getSelection();

sel.setPosition(div, 0);
sel.modify("extend", "forward", "word");
sel.modify("extend", "forward", "paragraph");

document.execCommand("JustifyCenter");
</script>