Simple fix for the flickering issue using a div overlaying the viewport

[guinnberg]

I think this is a really simple change and fixes the issue. Please if you reckon that it could be done in a better way just let me know, since this is a feature I really would like to have in my app.

[nervgh]

Maybe, you mean

if (event.currentTarget !== self.element[0] || !self._dragingOver) return;

instead

if (event.currentTarget !== self.element[0] || !self._dragingOver) return;

?

Try

/**
 * Event handler
 */
FileDrop.prototype.onDragLeave = function(event) {
    this._dragingOver = false;
    if (event.currentTarget !== this.element[0] || !this._dragingOver) return;
    this._preventAndStop(event);
    angular.forEach(this.uploader._directives.over, this._removeOverClass, this);
};

[nervgh]

fixed #286

[guinnberg]

I see that you merged other fix for this issue, but it has a bug that in my case wasn't happening. When you drag a file over the layer it doesn't flicker anymore (goooood!) but if you don't drop it, or drop it outside of the browser, the class is never removed.

BTW, maybe I'm blind, but I don't see the difference in what you're saying in the code lol. Anyway when _dragingOver is true, means you're draging so that's why I don't want the leave event to be fired, I'm also using the timeout trick to be sure it's not executed to soon, if it's not used, sometimes it still flickers.

What do you think?