Paint is with the best Thing, you can do this.
Like a Image-Map, you can Code Regions, where you can Click on Mouse, to select the Color.
The Thing is, that when you use Controls for each 255 Color's, the Overhead of TObject, and
the Class stuff will be included by each Control.
But, you can Test it by reduce these Information's by using seperate derived Sub-Classes, that
contains lesser Information's as the "super" Class.
This would not be flikker free, but this could be a Deal with using OOP-Classes with Hand Coded
the Components (and/or Bounding-Boxes).