when you enter face select mode the vertex colors are set to the ones specified in the paint buttons
at one time this [and the face buttons] were always visible in their own panel, but now they are only visible when you are in face select mode [the mode buttons] and vertex paint mode [the color choooser thing]. You can be in both modes at once, you toggle face select mode with the F key, and Vertex paint mode with the V key.
the colors are multiplied by the texture color, so if they were black your texture would be black, white your texture would look just the same. Green will make your texture darker and more green [and so on].
you can copy flags [light, collision whatever] to all selected faces with the copy drawmode button. Also, you can set the vertex color of all selected faces with the set vertex color button. This, like when you first enter face select mode, will set the color to the color used for vertex painting which isn’t visible if you aren’t in vertex paint mode.
[I kinda think both tabs should show up when you’re in face select mode…]