Delay on draggable items.
When you have draggable items all around the site (not that much but many of them). 
If you try to scroll (on mobile devices) you may activate the draggable event of an item. So in these cases it would be useful if it waits some time (customizable) before it starts dragging the item.
Something like in jQueryUI: http://jqueryui.com/demos/draggable/#delay-start