title: Mess with data inside class w/ databinding
body: <p>Im trying to edit some data within a class which is linked to with databinding. Here is my class:</p>
  
  <pre><code>public class Line
  {
      public string Equation { get; set; }
      public int PreviousLine { get; set; }
      public int LineNumber { get; private set; }
  
      public Line()
      {
          this.LineNumber = (this.PreviousLine + 5);
      }
  }
  </code></pre>
  
  <p>however the line number always returns 5, even if previous line is set to 6...</p>
  
  <p>here is how I link to it within my viewmodel:</p>
  
  <pre><code>this.Lines.Add(new Line { Equation = "5*2", PreviousLine = 6 });
  </code></pre>
  
  <p>thanks</p>