How to get fine resolution on the WinMLS mixer and signal generator slider?

The signal generator slider (shown at the bottom of the figure below) and WinMLS mixer input and output level sliders can be set using the mouse, but moving only one step may be difficult with the mouse. To move in single steps, do the following:

First click on the slider to set it active (a dotted border around the slider tells that it is active, see the figure to the right).  Then use the arrow keys on the keyboard to move in single steps.