20121114: Touchpad two-finger-tap gesture by John LeMasney via 365sketches.org #design

On Mac OS X, some applications, like GIMP and Inkscape, use ctrl combinations for other purposes, rendering a ctrl-click (like a right-click, brings up a contextual menu) inoperable. In cases where a touchpad is present, a two finger click works equally well. You might also consider connecting a two-button mouse, though given the touchpad solution, it may be unnecessary.