Currently, this cannot be achieved in the RadColorPicker. You can bind RadColorPaletteView to a collection of colors but you cannot make only a part of them "selectable".
We are currently working on creating a EditColorView which will act like a Popup and when you are to create a new color, you will be only able to work inside the view. This control should be ready for the Q2 2011 scheduled for the middle of July.
All the best,
the Telerik team
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