Drag&Drop in JCEF on Linux does not work

Background

I am working on a plugin which contains a web page using JCEF. It allows users to drag&drop web doms. It works fine on windows and mac but not Linux.

How to reproduce

Here is a simple drag&drop html demo. Upload ID "2021_10_30_T2bovR16SDANZ1Ej"

Just open it in any JCEF in IDEA. 

It work fine on Windows:

But it is not working on Ubuntu(18.04 & 20.04 | GNOME & Xfce):

What may happen

I dig a little bit. And I found that swing component are not handling drag&drop events on Windows. It seems that JCEF took care of these events. However on Ubuntu, somehow it envokes "dragEnter".

Chrome on Linux works fine. Even popup window of JCEF works fine.

I'm stuck now. Please help me to get drag&drop on Linux get working.

Thanks!