title: Best practices for creating libraries that use .NET namespaces
body: <p>Is it bad practice to write a library that defines an interface dependent on another library?</p>
  
  <p>I know tight coupling is bad, but does this still apply when using .NET classes?</p>
  
  <p>For example, in .NET, if I have a library that returns a Color object, it would force a dependancy on System.Drawing on anything that uses my library.  Would I be better off creating my own Color-type class inside my library? </p>