ColorBox control looks by default like on the picture below. Its main goal is to allow user to select one color from the list of available colors. The control can have simplified list of colors, extended list of colors, or custom one. By default it represents extended list with all web colors included. There is also special color called "None". This color is {0, 0, 0, 0} which means all its channels are zero and it is invisible.

ColorBox control(widget)

Although you can change properties of individual items(colors) in Form Builder, these changes will be lost by default. To store it you have to either add or delete any item. This action will convert control into custom one and all changes to individual items will be preserved during save, load, and export process. The control remains custom one untill you change one of the properties which changes the list of colors. They are HasStandardColors, HasExtendedColors, and HasNoneColor.