There are several keyboard/mouse click combinations that control Stylus RMX features:

Command / Control-Click Sliders or Knobs

Returns any slider or knob to its default position.

Shift-Click Sliders

Allows for precise adjustment of sliders.

Shift-Click Part Play Buttons

This combination allows you to control the All Play and All Stop functions while keeping the mouse over the Part Play buttons.

Right / Control-Click FX Slots

This reveals a drop-down menu that lets you use the FX Patch features.

Right / Control-Click on the FX Page outside the FX Rack

This reveals a drop-down menu that allows you to load and manage FX Rack presets.

Option-Click Knobs

Temporarily switches modes between linear mode and circular mode. In circular mode, you move the mouse in a circle around the knob after clicking on it. Moving the mouse to the 7:00 position of the circle sets the knob to its minimum value. Moving the mouse to the 5:00 position sets the knob to its maximum value. In linear mode, move the mouse up and down after clicking on the knob. All the way down sets the knob to its minimum value, and all the way up sets the knob to its maximum value. Circular mode allows for more precise adjustments, but linear mode is sometimes easier to use. The default mode is set by your host, but you can temporarily switch to the other mode by holding down the Option key when clicking on the knob.