WowAce

It is not possible to be perfectly accurate with the current Color Picker, because it is completely mouse-operated. There are no options to input specific numeric values. This makes it impossible to use the exact same color in multiple places throughout a UI. Being able to control our use of colors throughout a user's UI can help unify it, blurring the line between our addons and the Blizzard UI.

This could be addressed in Ace3 just as it is addressed in other software. A serious of text boxes might be added to the UI for the Red, Green, Blue and Alpha values. These might even be hidden from view by default, but remain accessible with a click for advanced users. At the moment I have to edit my WTF files manually in order to achieve accurate and explicit color settings, which is time consuming and prone to error.

-- getting a little crazy, below --

Something I'd really like to see is an accessible list of presets from the Blizzard defaults. The class colors are a big one here, but also presets for each of the different font colors Blizzard use, and debuff types, for example.

An interesting way of extended the Color Picker would be to imitate Adobe and have multiple tabs (complete with their own textboxes where it makes sense) for the various ways we select colors: RGB, CMYK, that crayon box thing, etc.

There are already tiny addons that improve the color picker, and which work with Ace3. For example: http://www.wowace.com/addons/enhanced-colour-picker/

We won't be doing this in Ace3, but you (or anyone else) are welcome to write this stand-alone and just replacing the default color picker.