how to preload all the images and sounds? indicator for objects with more than 1 image change image version to v1 when object drops in the queue?
layout mit flexbox? add card deck to the main page limit object drag to window borders? might wanna use .switchClass() from jquery ui?? (instead of .removeClass('v1').addClass('v2')
set img draggable = 'false' for all browsers - code from https://www.redips.net/firefox/disable-image-dragging/