OK! Many of you asked for the 3-button patch so here it is:

===================================================================
RCS file: /home2/CVSROOT/NetBSD/sys/arch/amiga/dev/ms.c,v
retrieving revision 1.1.1.8
retrieving revision 1.1.1.1.2.9
diff -c -r1.1.1.8 -r1.1.1.1.2.9
*** 1.1.1.8	1994/11/29 11:22:29
--- 1.1.1.1.2.9	1994/11/28 21:55:02
***************
*** 179,184 ****
--- 178,187 ----
  	pra >>= unit == 0 ? 6 : 7;	/* contains left button */
  	mb = (pot & 4) / 4 + (pot & 1) * 2 + (pra & 1) * 4;
  	mb ^= 0x07;
+ #ifdef EMULATE_3_BUTTONS
+ 	if (mb == 5)
+ 		mb = 2;
+ #endif
  
  	/*
  	 * read current values of counter registers

To install it just add EMULATE_3_BUTTONS as an option to your
config file, run config.new, remove your old ms.o, run make
and test your new kernel.  To get a middle button pressed
event, just press both the left and the right button simultaneously.
You have to be quite exact though, I didn't bother to implement
a more forgiving timing scheme.


Niklas