Pretty much any modern language will run on all the operating systems you mentioned, without having to modify the code. What you want is a framework/standard l

Pretty much any modern language will run on all the operating systems you mentioned, without having to modify the code. What you want is a framework/standard library to abstract away platform specifics. There are many alternatives out there but none of them delivers what they promise. One of the biggest problems is the lack of any standard GUI interface.