After using the View HTML tool the editor removes checked="checked" from a radio button.
Example:
<input name="ID" type="radio" checked="checked" value="1" />
becomes
<input name="ID" type="radio" value="1" />
It sort of works if HTML 5 is used.
<input name="ID" type="radio" checked value="1" />
will become
<input name="ID" type="radio" checked="checked" value="1" />
and will stay like that even if you view the HTML multiple times. But the next time the editor is loaded and the HTML is viewed checked="checked" will be removed.
it appears to work correctly for check boxes.