The Megacubo is made with PHP + Winbinder, using the miniPHP IDE.
PHP - http://www.php.net/
miniPHP - http://exvision.net/
The source code of the program is at the folder /components/etc/ relative to the install path of the program. It's a EPJ file called megacubo.epj and these files may be edited using the miniPHP IDE. You don't need to compile it again or use the "build" option of miniPHP, just save the EPJ file and run the megacubo.exe again. Everytime you load megacubo.exe it read, parse and run the megacubo.epj file, so any alter at the EPJ file can be viewed without any needs to recompile.
If you interested at the source of megacubo.exe, that read, parse and run the EPJ file, just look at the megamin.epj at the same dir, but you dont need to do it if you're only interested on modifying the program.