Jquery UI widgets on touch screens

Jquery UI widgets on touch screens

I've got some old code that used the jquery ui widget factory to implement some custom dragging functionality.  It's not working on touch devices and I'm trying to find the minimal modification that will fix it.  I've found that the jquery ui draggable demo ( https://jqueryui.com/draggable/ ) also doesn't work on touch---I can drag the box with mouse, but not with touchscreen.  I assume if I can fix that I can also fix my custom widget.  What's the right fix?