What I am seeking is a commonly used GUI editor program which we may see used in many game engines, if possible. I use GIMP and Inkscape, so I want to use one or both of them in the GUI creation pipeline. The jMonkey, Mono, and Unity3D engines I have in my computer but I would prefer to have my next GUI project here to be displayed on my screen as a console application with vector graphics but could embed rasterized images at a later time. I know some Java and C#, but I have heard about customizable GUIs which can be configured to simply open any folder or file, which I would prefer for this particular project. Windows is my OS. A cross-platform GUI editor program would be ideal but if it only targets Windows, then I can make use of that on some projects in the future.
My goal is to have a GUI displayed on my screen with at least one functioning button by this evening.
Any and all suggestions would be appreciated.