lEditCol        Edits a cell of the browse
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   TWBrowse::lEditCol( nCol, uVar, cPicture, bValid, nClrFore, nClrBack )

   This METHOD lets make a cell editing of any cell of the browse, at the
   currently selected row. It automatically creates a DialogBox with no
   border or caption, and that keeps one GET and one "OK" button. Only
   the GET will be visible and will fit exactly at the surface of the cell.

   <nCol>     The column to be edited.

   <uVar>     The initial variable value to be edited. You sould provide
              the same value that it is beeing displayed at the browse.
              Important: It has to supplied by reference: @<uValue>

   <cPicture> The PICTURE clause to be used at the GET.

   <bValid>   The VALID clause to be used at the GET, supplied as a
              CodeBlock.

   <nClrFore> A numeric value indicating the RGB text color for the GET.

   <nClrBack> A numeric value indicating the RGB background color for the GET.