Refactoring of Drag and Drop complete. Draggable properties isUsable, isOriginal included, but functionality connected with them is not complete. Found and fixed bug with z-index ordering.

New feature: Clicking on number for multiple icons on target will cycle all icons on target. Fixed bug with z-order ordering.

New feature: added ability to define custom label background color. Upated demo to use this feature. Needs to be turned on Python side.

New feature: when the draggable is out of the slider container, if it has a label, the label will get a background. This way it is much easier to discern the label against the base image.

Fixed annoying bug whre if you dragged any part of the base image or other parts of the Drag and Drop problem, then the browser would start highlighting the elements.

Added mouse event handlers to container of draggable. Now it is easier to initiate a dragging operation.

Added correct handling of invalid (missing) base images. Now error is reported, and the damage is reduced to a minimum.