Are you referring to IE11.10 or IE11 and IE10? I ask because Mendix does not officially support IE10 at this point: https://docs.mendix.com/refguide/system-requirements#desktop-browsers
If you're talking about IE11:
These 4 widgets have Mendix Platform level support. So, submit an issue on GitHub and open a Mendix support ticket, and these will get resolved.
These are not supported by Mendix directly. For drag-and-drop, your answers are correct. If you do fork the widget, please consider submitting a pull request to the widget author so that the problem will be fixed for everyone.
Finally, I'm the author of the ConfirmButton. Please add an issue to my repository and I'll take a look. Or if you happen to fix it yourself, I'll look out for a pull request.
If you want to make your custom widget work for IE use remove the line “use strict”; in the js file of the widget.
Complete help: