Function HandleTabInList(list as listbox, row as Integer, column as Integer, key as String) As Boolean
  // Handle tab character in Listbox.CellKeyDown event
  
  Select case asc(key)
  case 9
    if Keyboard.AsyncShiftKey then
      // back
      
      // look for column left
      for i as Integer = column-1 downto 0
        if list.ColumnType(i) >= list.TypeEditable then
          list.EditCell(row, i)
          Return true
        end if
      next
      
      // not found, so look in row before
      row = row - 1
      if row >= 0 then
        for i as Integer = list.ColumnCount-1 downto 0
          if list.ColumnType(i) >= list.TypeEditable then
            list.EditCell(row, i)
            Return true
          end if
        next
      end if
    else
      // forward
      
      // look for column right
      for i as Integer = column+1 to list.ColumnCount-1
        if list.ColumnType(i) >= list.TypeEditable then
          list.EditCell(row, i)
          Return true
        end if
      next
      
      // not found, so look in row below
      row = row + 1
      if row < list.ListCount then
        for i as Integer = 0 to list.ColumnCount-1
          if list.ColumnType(i) >= list.TypeEditable then
            list.EditCell(row, i)
            Return true
          end if
        next
      end if
    end if
  end Select
End Function