One option that is very well hidden: Click to fix the colour, and an up arrow appears at the bottom. From there, you can type in an RGB/hex/cmyk/etc code to cha

One option that is very well hidden: Click to fix the colour, and an up arrow appears at the bottom. From there, you can type in an RGB/hex/cmyk/etc code to change the colour, e.g. if you want to find colours to go with a specific one that's already in use.