ComboBox Commands
--------------------------------------------------------------------------------

 Creating a ComboBox         @ <nRow>, <nCol> COMBOBOX [ <oCbx> VAR ] <cVar> ;
 from source code               [ ITEMS <aItems> ] ;
                                [ SIZE <nWidth>, <nHeight> ] ;
                                [ OF | WINDOW | DIALOG <oWnd> ] ;
                                [ HELPID | HELP ID <nHelpId> ] ;
                                [ ON CHANGE <uChange> ] ;
                                [ VALID   <ValidFunc> ]

 Creating a ComboBox         REDEFINE COMBOBOX [ <oCbx> VAR ] <cVar> ;
 from resources                 [ ITEMS <aItems> ] ;
                                [ ID <nId> ] ;
                                [ OF | WINDOW | DIALOG <oWnd> ] ;
                                [ HELPID | HELP ID <nHelpId> ] ;
                                [ ON CHANGE <uChange> ] ;
                                [ VALID   <ValidFunc> ]


 <nRow>, <nCol>  The coordinates on screen. We simulate Text coordinates.

 <oCbx>          A reference to the ComboBox Object.

 <cVar>          A character variable which keeps the actual item selected
                 on the ComboBox.

 <aItems>        The items showed on the ComboBox.

 <nWidth>,       The dimensions of the ComboBox in pixels.
 <nHeight>

 <oWnd>          A reference to the container Object of the ComboBox.

 <nHelpId>       The help topic numeric identifier of the control.

 <uChange>       An action to be performed every time the selected item
                 changes.

 <ValidFunc>     An expresion to validate when the control is going to loose
                 the focus.

 <nId>           The numeric resource identifier of the Control.