We have a user experience designer in our team who has no programming background. He is expected to design screens within Eclipse as a development environment. His (valid) complaint is that every time he designs a specific screen and gives it to development - they tell him what is not possible technically using either SWT or GEF. So, he wants me to teach him basics of SWT/GEF so that he can make informed decisions and maybe even try out certain things in eclipse (as opposed to using Photoshop) before proposing designs to save time.

My personal belief is that design should not be constrained by technical possibilities and in theory, everything that the designer dreams of (at least the practical things) should be possible technically - albeit with workarounds or a little hacking.

So, my question is this - how important do you think is programming knowledge for user interface design? And if it is, how do you go about teaching someone with absolutely no programming experience the graphical frameworks on various platforms?