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!

Clearly X is broken if it assumes that sort of numbering :-) First, try
the magic new input device layer. If that doesn't fix it, we'd need a way
to recognize real two button mice from the ADB packets the busmouse driver
sees. If there's a clear way to tell the number of mouse buttons inside
the adbmouse interrupt handler I see no problem remapping 2 to 3 there
(other than the busmouse driver being OLD_CRAP and scheduled to
disappear).

FWIW: the assumption that the second mouse button is counted as middle
button is used throughout mouse_input and later code (even for the
inputdev sections). Think twice before you suggest breaking this.

	Michael


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