To access the HUD color Picker, with a painting tool selected, Control + Option + Command (Mac) -click and drag to select a color. On Windows, Shift + Alt + right-click and drag to select a color. The HUD Color Picker can be displayed as either a Strip or a Wheel. From Preferences > General, select the preferred display from the HUD Color Picker drop down menu. Note that both the strip and wheel options can be displayed at different sizes.
When the HUD color picker is displayed, continue to hold the mouse down while releasing the shortcuts keys and press the spacebar. The spacebar freezes the selection of the color and allows you to “jump” from the strip or wheel to the Hue/Saturation area (or vice versa) in order to refine one with out moving the other. Why would you want to do this? Well, you’ll quickly discover, that sometimes you have the correct luminosity and saturation selected but not the correct hue selected (or vice versa), and need to jump to the other portion of the interface to select it. This is a bit tricky when you first start using it, but makes the HUD color picker infinitely more useful.