function vGrow(yy, edge) {
      const c = matrix.findCellAt(sheetName, yy, cell.col);
      if (!c || !c.mark) { return false; }
      range[edge] = yy;
      c.mark = false;
      return true;
    }
function vGrow(yy, edge) {
      const c = matrix.findCellAt(sheetName, yy, cell.col);
      if (!c || !c.mark) { return false; }
      range[edge] = yy;
      c.mark = false;
      return true;
    }
function vGrow ( yy , edge ) { const c = matrix . findCellAt ( sheetName , yy , cell . col ) ; if ( ! c || ! c . mark ) { return false ; } range [ edge ] = yy ; c . mark = false ; return true ; }
grow vertical - only one col to worry about
grow vertical - only one col to worry about
grow the v - axis