The Edit Color window is very dated. It needs the ability to input hex color codes and should probably have an eyedropper as well. 

 
If I currently want to colour match something, I have to use the eyedropper in Photoshop and then break down the RGB values to input into Archicad.

 
 
I would suggest copying something like the Unreal Engine color picker which works well:

 
Rhino's Select Color window can also be used for reference:
