The ModBootstrap mod is a sample mod for developers to use to start creating ui/sim mods. Download it from the mod vault and start editing it.
It provides a working Mod Test Loop that you can use to instantly invoke changes to your files.
It provides a shortcut to launch FA with useful command line args, including logging and reloading.
It provides a bat file to kill FA in case it hangs.
Specifically, this mod creates a UI that shows the ID of the unit you have selected. When you change the ui code it will destroy the previous UI and create a new one, when you hit the save button.