That slider with very small indications of color change on the other sliders is a piece of crap! Are they saving pixels or what? There's plenty of real estate on the dialog to show the color in a blob big enough for you to notice and determine if you like the color. It also cracks me up that you have to change the color and open the menu or notification to figure out if it looks good - hahahahaha
One final thing - is the group responsible for color at MS color blind. Why pick a color and have it splashed on teh menu and notifications with only a minor adjustment to lightness? Every time I try it the tiles on the 'window' get washed out - what a dumb idea. It goes along well with pick a color from the icon and making the tile the same color (blue icon - blue tile) - but at least they're working on that.
But I was thinking more along these lines:
or even better, the old color customization dialogs (I know they're there, I can't find the dll or how to bring out the Hellman's). The metrics are still in the registry and value-attribute pairs are in .theme files. Having the dialog box beats opening a file or mucking about in the registry - plus you get a 'preview'.
cue the "it's not done yet" chorus