XPmouseKey()
 equivalent to Inkey, handle Mouse
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  Function:    XPmouseKey()

               XPmouseKey() has the same functionality as the inkey(0)
               function, with that difference that it will return 13
               (Enter, K_ENTER) when the left button is pressed and 27
               (Esc, K_ESC) for the right button (And now, also 32 (Space,
               K_SPACE) for the Middle button. You could thus use
               XPmouseKey() everywhere in your application where Inkey(0)
               (ie. wait for a key) was previously used, especially
               handy for the 'Press any key' and alike messages, where
               users generally assume that clicking the mouse is also
               good enough.

               This function does not require a Mouse to be installed,
               but just uses it when XPmouseThere() returns true. This
               function will not make the Mouse cursor visible, as
               there's nothing to move to.

               The value of Lastkey() will be set, even if a Mouse
               button has been pressed.

  Syntax:      XPmouseKey()

  Arguments:   None.

  Returns:     Keyboard code exactly as Inkey(0), and 13 for Left
               button and 27 for right button.

  Usage:       Msg('Press any key to continue')
               MouseKey()

  Note:        This is a simple function, just written to facilitate
               using those "press any key messages". It is not intended as
               a serious replacement for all you keyboard input.

               A look at the source code informs you it is quite simple:

               #include "EXPAND.CH"
               #include "INKEY.CH"

               Function XPmouseKey()
               /* Just as Inkey(0), with Mouse */
               Local i
               if XPmouseThere()
                  i := inkey()
                  while i = 0
                     if XPmouseRight()
                        While XPmouseRight() ; end
                        i := (K_ESC)
                     elseif XPmouseLeft()
                        While XPmouseLeft() ; end
                        i := (K_ENTER)
                     elseif XPmouseMiddle()
                        While XPmouseMiddle() ; end
                        i := (K_SPACE)
                     else
                        i := inkey()
                     end
                  End
               else
                  i := inkey(0)
               end
               Return (i)