C1FlexGrid for Silverlight and WPF has many things in common with the WinForms version, including much of the object model, but they are not identical. There are two main reasons for the differences:
Mouse and keyboard handling, for example, are different between WinForms and WPF or Silverlight, and so is the imaging model, data binding, dependency properties, etc.
We did map all of the properties, methods, and events that made sense and 'felt right' in the new platform, but we had to strike a balance between making the control feel like "the WPF and Silverlight version of C1FlexGrid" (which we wanted) and not "a WinForms grid that works in WPF and Silverlight" (which we did not want).
We worked hard to allow developers to take advantage of new platform features, but not force them to change the way they work. For example, you can change the look and feel of the grid by working with a designer and changing the control template in Microsoft Blend. But you can also do it by implementing a simple CellFactory class in C# or VB.
The original WinForms C1FlexGrid is a stable, mature control that has been around for 10 years now (or a lot more if you count the ActiveX version that came before that). Over this time, we learned a lot about what features are important and how they should be implemented.
We took all of this experience and used it to make the new C1FlexGrid the simplest and most powerful version yet.