title: VB.NET: Add additional functions to a class
body: <p>the "Rectangle" class does not expose all the functions that I would need to manipulate the rectangle.
  For example, I often want to change the ".Bottom" value only. 
  None of the existing functions allow me to do so, and I find myself creating a new rectangle to do what I need.</p>
  
  <p>This brings me to a general question:
  Is it possible to add additional functions to a class in the framework that are then available in my entire project?</p>