In Moom's hover overlay, windows are shown as white against a black background. But in Moom's menus, and in the drop-down menu below the Moom hover overlay (if enabled), windows are shown as gray on a white background. You may wonder why this isn't consistent ... so here's the explanation:

The reason for the switch is that the contexts differ. In our opinion, the zoom button overlay works better when displayed in inverted "HUD" style, while the custom control editor is a plain old "dark controls on light background" window, so the grid controls match that there.

So while the absolute colors aren't the same, there actually is a common design principle between these two: Highlighted areas contrast strongly with the window background color, while non-highlighted areas are displayed in a color that is close to the background color. That way, the interesting bits get more attention.

However, if you think this is wrong, you can switch it. Quit Moom, open Terminal, paste this line, then press Return:

defaults write com.manytricks.Moom "Invert Overlays" -bool YES

Now relaunch Moom, and you should find the color scheme inverted. (To switch back, repeat the above, but change YES to NO.)