[whatwg] Should UA start dragging if [draggable] attr was set after mousedown?

[Даниил Костин]

Hello. I am web developer. I contribute to the ACE (ace.ajax.org) project
(web-based code editor).
I faced with the issue that IE does not start dragging element if it's
[draggable] attribute was set with some delay after mousedown event:

element.draggable = false;
> element.onmousedown = function() {
>     setTimeout(function(){ element.draggable = true }, 150);
> };


Meanwhile, this works fine in other browsers. I tried to find this behavior
to be defined by DND specification (
http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#dnd)
but found nothing related.
I reported the bug (
https://connect.microsoft.com/IE/feedback/details/799913/ie-8-11-ignores-draggable-attribute-when-set-after-mousedown-event-using-settimeout)
but I am not sure this is really bug.

May we we should add more specific explanation of DND initiatialization, to
prevent such kind of misunderstanding?