I've recently came to C# to Java to see if I could get any success creating an application in this way, by creating a few window tests.

I want to do this in pure code (like I did in Java), and want a library similar to Java's java.awt.*+javax.swing.*.
And, I found something that looks suitable, System.Windows.Form, but, as far as I've read, and as the name (kinda) implies, it's windows exclusive.

Is there any cross-platform library that accomplishes the same things, with a similar formatting (to that or the one in Java)?

Thanks!
Cheers!