Remove duplicate "down" events

[AStoker]

Resolves: #972
Related: #1000
Removes duplicate “down” events and preventDefault operation on click
events on “filter” items. This allows selection of things like text
boxes and input elements that are inside a sortable element.
Repro of bug: http://jsbin.com/cerumanoma/edit?html,js,output

[fourpixels]

Why isn't this accepted?

[RubaXa]

Removes duplicate “down” events

Your solution is incorrect, you can not suscribe on one of the event, should always subscribe to both, because the user can be simultaneously be two input devices: mouse and touch-screen.

So need a different solution.

Removes preventDefault operation on click events on “filter” items.

That means you should not use the "filter". Now this method is implemented exactly as designed.

[RubaXa]

Added preventOnFilter: 1aa0121

[RubaXa]

Removes duplicate “down”

Try master: a7cddbc

[geonanorch]

I was about to open a new issue when I found this one.
I am not 100% sure that it is the same problem, but there is definitely a problem of duplicate filter event:

the test which would filter duplicates (and in particular reading of lastDownEl):

if (lastDownEl === target) {
	// Ignoring duplicate `down`
	return;
}

comes before the dispatch of the filter event, which causes processing to abort with a return:

_dispatchEvent(_this, criteria, 'filter', target, el, el, startIndex);
return true;

But setting of lastDownEl only takes place later in the normal case, not when filtering was triggered:

_prepareDragStart: function (/** Event */evt, /** Touch */touch, /** HTMLElement */target, /** Number */startIndex) {
  . . . . . . .
lastDownEl = target;

Imho the assignment of lastDownEl should take place right after the duplicate check:

if (lastDownEl === target) {
	// Ignoring duplicate `down`
	return;
}
lastDownEl = target;

But I do not know the code well enough to be sure that there are no side-effects.
Still, I hope this helps,