Primary and secondary color selector
The selector holds two colors, the primary and the secondary color. These colors can be selected using the color picker, or by changing the mixer values, selecting a existing color in the palette or by using the eye dropper tool to select a color in the canvas. The current tool will only draw in the primary color, however the primary and secondary color can be toggled using the X key, providing quick access to two colors whilst drawing.
You will notice the double line rectangle in the selector, this emphasizes the color selector item (i.e. primary or secondary color) that will be affected by actions in the color picker, the mixer, ramp selection or palette. If you move the marker in the color picker, or select a color in the palette, the new color will be assigned to the color slot in the selector depending on whether the primary or secondary color has the double line indicator. In the example below, clicking on a color in the palette will assign that color to the secondary color slot.