I used
Clickteam's Multimedia Fusion 2, which allows you to quickly create applications without scripting. I also used it for the GUI in my old level editor (the important code was written in C++) and my save editor.
Edit:
Update: Some (if not all) of the global switches are automatically enabled and disabled by a combination of one or more super-global switches. For example, the switch for the electric wall connected to Bonewerkz which guards FeeCo Ender is enabled (i.e. wall is off) if the Visited Bonewerkz super-global is on, but disabled when the Visited Feeco Ender super-global is off. This switch is calculated on request, i.e. when the an object using this switch is loaded to the screen.