Set browser agent to a mobile agent in Chrome developer tools > "..." menu > more tools > network conditions tab.
This will cause the browser to load the domtouch.js (touch events handling) while the browser has also mouse events.
NOTE: this is an incorrect use of browser user agent BUT it's the easy way to reproduce the conditions on a hybrid device such as a "Surface" PC tablet, or a windows 10 desktop using a touch-enabled monitor with the win10 touch driver.
Click button to open modal window
Drag mobile window
Mouse cannot drag the modal window (touch events may drag)
Both mouse and touch should be registered
Event types are defined in dom.js
domtouch.js replaces the original entries for 3 events (mousemove, mouseup, mousedown) buy their touch equivalent. However, since they replace them using the same event key (zmousemove, zmouseup, zmousedown), the original mouse events are removed from the event types.
full replacement file for domtouch.js (Ask support team)