I am not quite sure what you mean by saying that you center the RadColorPicker on the client. In case you calculate the position and apply it to the palette of the RadColorPicker and that position is not the one you expect, perhaps there is a problem in your calculations. Please note that when you apply position to an element, it is relative to the first positioned parent of the element. In case you send me a simple test page, demonstrating how your code works, perhaps I can explain the result you get and point you in the right direction.
As for your second question - yes you are correct, you have to apply "position:relative;" to the element that you scroll. I tested it and the color picker scrolled with the rest of the content - please find my test page attached. Could you please send me a test page, demonstrating your setup, so that I can research what is causing the problem?
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