I am using IntelliJ IDEA 9.0.2 on Mac OS X - with the Magic Mouse. Whenever I press the command button and move my finger a micrometer or two on the surface of the mouse, IDEA i
IntelliJ IDEA 14.1
By default it is disabled and it can be found here:
File > Settings... > Editor > General > Change font size (Zoom) with Ctrl+Mouse Wheel
The option is still there in IntelliJ IDEA 15 EAP.