Both Furniture and Texture Library Editors work directly under my installation of Win 10 (upgrade from 8.1).
However, Win 10 upgrade did mess with several file associations and extensions. Win10 seemingly uses additional ways if deciding how files should open. Or it could be that Edge/Internet Explorer under Win10 has added another (hidden) extension/association to the file during download.
.jar extension here is set to work with Java(TM) Platform SE binary (just like original configuration under Win 8.1).
If that does not work, you could of course try Linux
ok
