Emulating button 3 on 2 button ADB mice.

[Malcolm Purvis]

There is a problem in getting XFree86 4.0.1 to emulate the third mouse button
with two button ADB devices, in my case a Kensington 'Orbit' trackball.
Reviewing the archives, I see that variations of this problem have appeared in
the past but there never has been a well publicised solution.

In summary, my problem is:

1) The two buttons on the trackball map to buttons 1 and 2, when ideally they
   should be 1 and 3.

2) I cannot get XFree86 to emulate the third button when I hold down both
   buttons at once.

It should be noted that a message was posted to this list nearly a year ago
that exactly describes my symptoms:

<http://lists.linuxppc.org/listarcs/linuxppc-dev/199909/msg00135.html>

The suggested solutions, of using mousemode and xmodmap and the
Emulate3Buttons XFree86 option, did not work for that poster, and it didn't
work for me.

The cause of the problem is that the kernel (in adbmouse.c) generates busmouse
messages with the trackball buttons assigned to 1 and 2, but XFree86 (in
input/mouse/mouce.c), when emulating the third mouse button, expects two
button mice to have buttons 1 and 3!

(Note that this is cannot be fixed with xmodmap because it is the button
numbers the device driver is returning, not the X server.)

I have written a small hack for XFree86 that switches buttons 2 and 3 on bus
mice when appropriate.  The question is, is this the right place to put the
fix?  It's a very device specific solution, so really shouldn't go in user
space but, conversely, how many other programs expect the kernel to set
buttons 1 and 2 for two button mice instead of 1 and 3?

I welcome suggestions as to where to put the fix so I can submit it to the
right people.

Malcolm


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