Answer 1

Windows, or graphical? Even many languages which do not have the capability to handle a graphical UI themselves have a toolkit that makes it possible. Also, most of the popular modern languages are not specific to any OS so they tend to run on Windows + others.

Java, Python, C, C++, Perl, HTML/CSS/JS, BASIC and more are all capable of a GUI. C# is too, but requires using Mono on Mac/Linux as Microsoft's .NET framework is not supported otherwise. Objective-C & Swift can do GUI programming too, but are specific to macOS/iOS.