POPMENU ( aPop, nTRow, nLCol, nBarRow ) -> nChoice

   Creates a PopUp-Window and returns the chosen Row.
   Colors are predefined via SetPref().


   PARAMETER:

       aPop      Array with 4 Dimensions:

            <cText>, <xRet>, <lSelect>, <cMessage>, <cShortCut>

       nTRow     TopRow of the MenuWindow
       nLCol     LeftColumn of the MenuWindow
       nBarRow   Row, in which the MenuBar is set
                 needed for the Mouse: If the Mouse meets the MenuBar
                 all Windows will be closed
                 (ReturnValues = K_MOUSE, otherwise K_ESC)



   RETURN VALUES:
   ReturnValues of the Menu:

   If it's a valid choice the 'aBar [x, nRet]' value, defined
   in the MenuArray, will be returned.
   Unless:

   you defined a SubMenu-Array in it -> this will result in a PopUpMenu

   or

   a defined a CodeBlock in it, which sets the .-Tag.
   In this case nothing will be returned, because the Menu is not canceled.

   The following ReturnValues are predefined (SoundVis.ch):

       B_ESC       0   will be returned if ESC is pressed
       B_LEFT     -1   Cursor Left  -> Internal, MenuItem +1
       B_RIGHT    -2   Cursor Right -> Internal, MenuItem -1
       B_MOUSE    -4   Internal, new Menu chosen by Mouse



   Structure of the MenuArray:

   Each element of the array has at least one and a maximum of five
   dimensions. You'll find the defines in SoundVis.ch ( again )

   aPop [x, MEN_TEXT]  cText
          MenuText, Hotkey is the character after the HotKey-Marker '~'
          If {A_SEP} is put here, PopMenu will draw a seperation-line
          In this case (and only in this case) the element hast only
          one dimension !

   aPop [x, MEN_RET]   nRet
          A numeric ReturnValue cancels the Menu and returns this value,
          a SubArray in here pops up another Sub-PopUpMenu. If a CodeBlock
          is in it, the ReturnValue ( .T. or .F. ) will set the
          CheckMarker '.' ( .T. means set, well... )

   aPop [x, MEN_SEL]   lSel
          is this Item selectable ? if so -> put .T. in here

   aPop [x, MEN_DESC]  cDesc
          Description of the MenuItem, the Hotkey-Marker '~'
          will display the following word in a different color

   Optional:
   aPop [x, MEN_CUT]   cText
          Description of the ShortCut key-defines, like, for example
          'ALT-F4' might get you back to DOS ( hello, Windows )