Xhpc - middle and right click

Hello all,

the question was already raised in this mailling list but I couldn't find
the answer : in the documentation for Xhpc, it is sais that :

     The pointing device can be the touch panel, or USB mouse.  Touch panel
     supported on NEC mobile Gear Series.  USB mouse supported on Sharp
     Telios.

     the touch panel can emulate 3-button mouse.

     -just touch
                 = click left button

     -[win] + touch + 2
                 = click middle button

     -[win] + touch + 3
                 = click right button
     Also, you can use 4th and 5th button.

I tried this with Xhpc and Matchbox (Generic Kernel 3.0.1) and couldn't find
the trick.  Applications like xpdf use sometimes the right click for special
functions (xpdf needs right click to load files).

Regards

Alain