if i create object 'gcanvas', i can move the inputs but the actual box stays in the same place (until I minimise/maximise). Is this a known issue?

"gcanvas" is not a very commonly used object (in fact, I'd never come across it until now! A lot of the objects that you'll find at the bottom of those Extended folders are buggy and unmaintained. Unfortunately, you probably won't get anywhere by reporting issues, as the developers no longer support Extended.

What exactly are you trying to do? There's a good chance that there's another way of accomplishing it using more conventional objects.