<p>Caret should be hidden when no focus</p>
Manual steps:
<ol>
<li>Click middle of "edit me!" to show caret.</li>
<li>Click checkbox.</li>
<li>Caret should be hidden.</li>
</ol>
<div contenteditable="true">edit me!</div>
<input type="checkbox">
<script>
document.querySelector('div[contenteditable="true"]').focus();
if (window.eventSender) {
    var checkbox = document.querySelector('input');
    eventSender.mouseMoveTo(checkbox.offsetLeft + 5, checkbox.offsetTop + 5);
    eventSender.mouseDown();
    eventSender.mouseUp();
}
</script>