Hey, guys, I am a Chrome Extension/Firefox Addon developer. I found it does not work in the Firefox addon popup window, but it works in debug tab window and split window. And HTML5 origin drag and drop runs ok.

here is my demo: https://github.com/vanishcode/firefox-addon-test

screenshot:
https://user-images.githubusercontent.com/20496444/220562746-01f7398c-70f9-44e0-ba06-9ac2900e14b7.mov

update:
On the Chrome extension popup window, the 'end' event would be triggered, but in this Firefox case, 'cancel' would be triggered.

Thanks!

I fixed it: in the Firefox addon popup window, the code below will be triggered:

Thanks also!