Hello Jason Parrish,
Thank you for writing.
You can edit the properties of the spin editor in the RadPropertyGrid EditorInitialized event. Here is a code snippet which demonstrates this:
The reason for the NewValue and old value to be of different types is that the old value is the value of the property and the new value is taken form the editor. And since we have one editor for all numeric types there will be differences.
I hope this explains things. Should you have further questions I would be happy to help.
Greetings,
Ivan Petrov
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.