Tk Toolkit

Pressing the rightmost button on my 3 button mouse generates a
Tk event saying button 2 was pressed, while pressing the middle
button generates an event saying button 3 was pressed. This is
on Aqua Tk 8.4.1. Other applications on my Mac, such as the X
server identify the rightmost button as button 3 and the middle
button as button 2. Only Tk appears to reverse buttons 2 and 3.

The following wish8.4 script will display the button number
associated with button presses.

bind . <ButtonPress> {puts "%b"}

Pressing my 3 mouse buttons from left to right, prints 1 3 2.