Newer versions of HTML introduce features like the
contenteditable="true" attribute (for example).
Can new HTML features be added to the supported HTML on Stack Exchange sites, or is the list of allowed HTML tags frozen.
The Wikimedia projects decided to ban dangerous HTML features as well as those which are not useful. Moreover, the wiki syntax is considered powerful enough. So it won't change even if useful features are found.
Is it the same policy in effect for Stack Exchange sites (with Markdown in place of wiki syntax)?