XPmouseSet()
 Globally set the status of the Mouse
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  Function:    XPmouseSet()

               .t. by default, The mouse can be set OFF at all times
               by selecting XPmouseSet(.f.). This van be handy when one
               explicitly does not want to use the Mouse.
               When XPmouseSet() is set OFF (.f.), XPmouseThere() will always
               return .f., by which it seems there is no mouse. When
               XPmouseSet() is ON (.t.), XPmouseThere() returns .f.
               in any case. Execute XPmouseSet(.t.) for XPmouseThere() to do
               actual checking, XPmouseInit() always works, btw..

               XPmouseSet() in ON by default.

  Syntax:      XPmouseSet([lMouse]) --> lMouseSetting

  Arguments:   .t. Indicates that you would want to use the Mouse if
               present. .f. indicates NO, NO MOUSE!

  Returns:     The current setting of XPmouseSet().

  Usage:       You may want to leave it to the user, in the Options menu
               of you application, to decide whether (s)he wants a Mouse when
               available.