This application is an experimental color palette that could be used as a teaching tool to demonstrate how colors are created on the computer using the RGB model. Most of us learned to mix colors as children following a pigment-based color mixing model, where white is the absence of color and the addition of pigment leads to a more saturated hue with the complete combination of all primary colors yielding black.
Creating screen based color is a quite different process. It is based on the theory of colored light, where black is the absense of light and white light is created by the perfect combination of red, green, and blue. Using this model, the user starts with a black palette (i.e. the absence of light or RGB = (0, 0, 0) and creates color by incrementally adding bits of colored light by dragging the swatches onto the mixing palette in the center of the stage. There are six swatches to represent the three primary colors: red, blue, and green, and the three intermediary colors: magenta, cyan, and yellow. Notice that as more color is mixed, the resultant color becomes brighter, but not ncessarily more saturated. If one thinks of saturartion as a certain purity of color, you can start to see where adding more different primary colors to the mix tends to grey out the result and make it ultimately approach white.
Try the palette for yourself and see!