I have to develop a GUI editor for something that's not Swing or the
like (so, can't use existing editor for Java GUI).
I have all infos about the elements (position, size, type, etc) and I
have to read that data, modify the layout visually, then write it
back.

The missing part is the implementation of the editor itself, and I
have no idea on how to proceed.

Can anybody give me an hint? Can I adapt an existing software somehow?
Can the Matisse GUI editor in NetBeans be used for something different
from Swint/Java, maybe XML?

Thanks in advance.

Raffaele