Apple’s PowerBook built-in touchpad has no middle or right mouse button. Under Mac OS X, right-click is simulated by holding down the Control key and then clicking. However, this doesn’t work on Ubuntu Linux.

Googling around, I found that, by default, the F11 key is mapped to a mouse middle-click while the F12 key is mapped to a mouse right-click.

It is also possible to change this behavior by editing /etc/sysctl.conf and mapping dev/mac_hid/mouse_button2_keycode and dev/mac_hid/mouse_button3_keycode to their corresponding key scan codes. The scan code for a key can be retrieved by running

sudo showkey

then pressing the key or keys for which the scan codes are to be printed. To exit, press Control-D.