WPF: Setting the Height or Width to Auto in Code
At times, you may want to programmatically set the Height or Width of a WPF element to Auto in code. To do this, just use the Double.NaN (Not a Number) value.
For example, in C#:
this.txtName.Width = Double.NaN;
And in VB .NET:
Me.txtName.Width = Double.Nan
Chief Architect, MM .NET Application Framework