Chelaru : Yeah, I think what I'll do is get everything functional and then identify the areas that lend themselves to being customized by the user and put it all into some kind of Look & Feel options menu. Two things off the top of my head are the material editor colors as you mentioned, and the script editor's syntax highlighter. I hope to add those plus a number of other options for user customization of colors and look/feel. Unfortunately a downside (or upside depending on who you ask) of wxWidgets is that it uses native window controls, so they adhere to your systems theme. For this reason I'm not sure I'll be able to achieve extreme customization, but I'll try to squeeze in options where ever I can.
saindd : No toolkit, I wrote them as a custom control in wxWidgets. It's practically the same code I used for the node editor in the old editor I just adapted it for wxWidgets. it's not that hard when you dig into it. I would say the hardest part is getting a good looking bezier curve for the connections between nodes.