Thank you for writing.
It seems that the information for this object ended up in our documentation before it is officially released in Q3 2011. Please excuse us for the introduced inconvenience.
In order to take advantage of this functionality, please upgrade your projects to our latest version - Q3 2011 (it is available for download in your account).
I hope that you find this information helpful. Should you have any other questions, do not hesitate to contact us.
All the best,
the Telerik team
Q2’11 SP1 of RadControls for WinForms is available for download (see what's new); also available is the Q3'11 Roadmap for Telerik Windows Forms controls.