The separate color correction dialog is for alterations that should not effect the entire image but only a specific colour
first thing to do after this dialog appears is to click on the large SilverFast preview on that area with the colour you want to edit.
The dialog will consider this colour as the basis to work from. You can see this - for example - in the colour at the centre of the colour-wheel.
This window has three alternative modes for the same task!
No matter wheter you drag the mouse cursor from the centre point of the colour wheel to any of the outer points or simply hold-click at any of the arrows of the HSL-sliders or directly enter values into any box of the above table, you are doing the same thing!