Put the summary of the bug you're having here

What I expected to happen was...:
I would right-click, allowing me to place a block

What actually happened was...:
I left-clicked. On a mac computer, you must hold the control-button to be able to right-click, because a mac mouse doesn't have a right-click button. I tried attaching a windows mouse (with 2 buttons, right and left) and it worked fine. So it works on my computer, but just not with a "mac" mouse, only a "windows" mouse. (I checked 1.5.2 to make sure it wasn't my mouse/computer, and everything is ok there as it has been. It just doesn't work in 1.6).

Steps to Reproduce:
1. Use a "mac" mouse (maybe in a mac computer, but maybe it's any computer)
2. hold control button
3. click (this should right-click, but instead it left-clicks)