I believe that it's HTML/CSS/JavaScript, and runs in a heavily customized browser. (Please no laughing at me. I'm sensitive, and my feelings are easily hurt)
it is not available anywhere that you can access it, unless you're an IT developer in that area that works for Bloomberg.
So that's got to be one of the clunkiest, most obtuse, counterintuitive, and difficult to learn UIs in regular use today, clearly kludged together over decades. I've gotta ask why in the world anyone would want their source code for anything except material for the "not that" portion of a "Do this, not that" UI course! Not helpful for you, I know. Perhaps more useful, if not exactly helpful, is knowing that everything Bloomberg is highly proprietary and not only impossible to legally obtain but radioactive from a lawsuit perspective if you ever did obtain or reverse engineer it. That way madness lies.
Will recommend this one http://doc.stocksharp.com/html/bb71ead8-62c4-47f8-a1aa-242d63d631fb.htm Free for use. Even for commercial. .NET component. How is your exchange? What the progress?