RadColorPicker supports a number of client-side events that let you customize behavior:
OnClientLoad: occurs after the color picker loads on the page.
OnClientColorPreview: occurs as the mouse hovers over a color box within the palette.
OnClientColorChanging: occurs just before the user selects a color from the palette. Can be cancelled.
OnClientColorChange: occurs when the user selects a color from the palette.
OnClientPopupShow: occurs after the pop-up palette of a color picker with ShowIcon set to "true" shows.