>I did not know that! (Actually I see 48 colors in VFP 9). I share your skepticism about how Microsoft knows these are the most popular colors. How exactly would they know that?

They knew that in advance, before that specific set of colors became popular. And it became popular because it's so much more easy to pick one of them than to tweak your own RGBs. Sort of a vicious circle, or generative speech. If you give a limited choice to 90% of computer users, and allow them a different choice at a single click of a button (plus the effort needed to actually exercise that choice) - then this limited choice will become extremely popular.