Mouse use in Logic Pro differs from mouse use in other applications.
Place the mouse pointer on the element (region, event, button, menu, input field, and so on) and press the mouse button once.
The same as clicking an element, but you press the mouse button twice—in quick succession. You can set a suitable interval between clicks in the System Preferences (Keyboard & Mouse pane).
The same as clicking an element, but you keep the mouse button held down.
Grab the element and move the mouse (keeping the mouse button held down) to the desired position.
The same as clicking, but you press the right mouse button, if available. This opens a shortcut menu, the Tool menu, or selects an assigned tool.
Many commands, functions, additional tools, or finer adjustments are accessed by holding down a modifier key—Control, Shift, Option, or Command—while clicking or dragging. For example, Option-dragging a region copies it. Option-clicking a fader or knob resets it to its default, or centered, value.
You can use the mouse wheel to scroll vertically in Logic Pro. There are also some modifiers supported:
If you press Command, the mouse wheel scrolls horizontally.
If you press Option, the mouse wheel zooms in or out vertically.
If you press Option-Command, the mouse wheel zooms in or out horizontally.
If you press Option-Control, the mouse wheel zooms in or out in both directions.
Note: Logic Pro also supports mice that feature an x and y axis on one scroll wheel (such as the Apple Mighty Mouse). On a 2-axis mouse, the Command modifier (that switches a single-axis mouse between horizontal and vertical orientation) is not used.