Would be a great Idea to join forces in one project to make a xul ide. Reusing part of nvu, adding the dom and venkman functionality. Code completion and so on... Would the mozilla foundation help to those who want to develop it?
About the IDE of OrangeVolt
I have gone to the website at sourceforge and found only a tutorial for a XSLT translator.
About a new IDE project for XUL
Let's see the XULBooster project.