How do different browsers handle empty paragraphs/blocks using contentEditable?

code.html

<!-- most modern browsers -->
<p><br></p>

<!-- ie9 -->
<p></p>

<!-- ie7-8 -->
<script>
document.body.appendChild(document.createElement('p'))
</script>

summary.md

Empty paragraphs would be those which have no editable content, but are still selectable via cursor and let content be added to them.

From my tests:

1. 'Modern' browsers (Chrome/Firefox) -- Adds a
   as the last element. This
   can't be edited/selected, but it keeps the tag artificially "open" whenever there's no other content in it. Can be written using HTML.

2. IE9 -- Empty paragraphs can be fully empty and still editable.

3. IE7--8 -- Empty paragraphs are fully empty and still editable. However, innerHTML reads as though there was an   in the paragraph (there's not). Also, manually writing <p>&nbsp;</p> in HTML actually adds an editable space, but <p></p> isn't editable! Turns out this works only if you add an empty paragraph via DOM methods (with no inner nbsp)

tags.json

["innerhtml","contenteditable","space","html","dom","ie","browers","compatibility"]

maybe a bug in webkit since 2005
https://bugs.webkit.org/show_bug.cgi?id=4003