Steps to Reproduce

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.

Open fiddle:

https://zkfiddle.org/sample/3u27amp/1-Another-new-ZK-fiddle

Click button to open modal window

Drag mobile window

Current Result

Mouse cannot drag the modal window (touch events may drag)

Expected Result

Both mouse and touch should be registered

Debug Information

https://tracker.zkoss.org/browse/ZK-4301

Event types are defined in dom.js

https://github.com/zkoss/zk/blob/0efb2dbfa21ebf2cbec4b601375d1e1037000ed0/zk/src/archive/web/js/zk/dom.ts#L297-L303

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.

https://github.com/zkoss/zk/blob/master/zk/src/archive/web/js/zk/domtouch.js#L95-L99

https://developer.mozilla.org/en-US/docs/Web/API/Touch_events/Supporting_both_TouchEvent_and_MouseEvent

Workaround

full replacement file for domtouch.js (Ask support team)