Private Sub Worksheet_SelectionChange(ByVal Target As Range)
  Static EskiHucre As Range
  If Target.Interior.ColorIndex <> xlColorIndexNone Then
    EskiHucre.Interior.ColorIndex = xlColorIndexNone
    Exit Sub
  ElseIf Not EskiHucre Is Nothing Then
    EskiHucre.Interior.ColorIndex = xlColorIndexNone
  End If
  Target.Interior.ColorIndex = 6
  Set EskiHucre = Target
End Sub