ขอสอบถามเกี่ยวกับ Code VB 2010 เกี่ยวกับการ Screen Resize resolution หน่อยคะ

Imports System
Imports System.Windows.Forms
Imports System.Runtime.InteropServices
<StructLayout(LayoutKind.Sequential)> _
Public Structure DEVMODE1
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=32)> _
    Public dmDeviceName As String
    Public dmSpecVersion As Short
    Public dmDriverVersion As Short
    Public dmSize As Short
    Public dmDriverExtra As Short
    Public dmFields As Integer
    Public dmOrientation As Short
    Public dmPaperSize As Short
    Public dmPaperLength As Short
    Public dmPaperWidth As Short
    Public dmScale As Short
    Public dmCopies As Short
    Public dmDefaultSource As Short
    Public dmPrintQuality As Short
    Public dmColor As Short
    Public dmDuplex As Short
    Public dmYResolution As Short
    Public dmTTOption As Short
    Public dmCollate As Short
    <MarshalAs(UnmanagedType.ByValTStr, SizeConst:=32)> _
    Public dmFormName As String
    Public dmLogPixels As Short
    Public dmBitsPerPel As Short
    Public dmPelsWidth As Integer
    Public dmPelsHeight As Integer
    Public dmDisplayFlags As Integer
    Public dmDisplayFrequency As Integer
    Public dmICMMethod As Integer
    Public dmICMIntent As Integer
    Public dmMediaType As Integer
    Public dmDitherType As Integer
    Public dmReserved1 As Integer
    Public dmReserved2 As Integer
    Public dmPanningWidth As Integer
    Public dmPanningHeight As Integer
End Structure

Class User_32
    Public Declare Function EnumDisplaySettings Lib "user32.dll" (ByVal deviceName As String, ByVal modeNum As Integer, ByRef devMode As DEVMODE1) As Integer
    Public Declare Function ChangeDisplaySettings Lib "user32.dll" (ByRef devMode As DEVMODE1, ByVal flags As Integer) As Integer
    Public Const ENUM_CURRENT_SETTINGS As Integer = -1
    Public Const CDS_UPDATEREGISTRY As Integer = 1
    Public Const CDS_TEST As Integer = 2
    Public Const DISP_CHANGE_SUCCESSFUL As Integer = 0
    Public Const DISP_CHANGE_RESTART As Integer = 1
    Public Const DISP_CHANGE_FAILED As Integer = -1
End Class

Namespace Resolution
    Public Class CResolution
        Public Sub New(ByVal a As Integer, ByVal b As Integer)
            MyBase.New()
            Dim screen As Screen = screen.PrimaryScreen
            Dim iWidth As Integer = a
            Dim iHeight As Integer = b
            Dim dm As DEVMODE1 = New DEVMODE1
            dm.dmDeviceName = New String(New Char((32) - 1) {})
            dm.dmFormName = New String(New Char((32) - 1) {})
            dm.dmSize = CType(Marshal.SizeOf(dm), Short)
            If (0 <> User_32.EnumDisplaySettings(Nothing, User_32.ENUM_CURRENT_SETTINGS, dm)) Then
                dm.dmPelsWidth = iWidth
                dm.dmPelsHeight = iHeight
                Dim iRet As Integer = User_32.ChangeDisplaySettings(dm, User_32.CDS_TEST)
                If (iRet = User_32.DISP_CHANGE_FAILED) Then
                    MsgBox("Unable to process your request")
                    MsgBox("Description: Unable To Process Your Request. Sorry For This Inconvenience.", "Information", MessageBoxButton.OK)
                Else
                    iRet = User_32.ChangeDisplaySettings(dm, User_32.CDS_UPDATEREGISTRY)
                    Select Case (iRet)
                        Case User_32.DISP_CHANGE_SUCCESSFUL
                            Exit Select
                        Case User_32.DISP_CHANGE_RESTART
                            MsgBox("Description: You Need To Reboot For The Change To Happen." & vbLf & " If You Feel Any Problem After Rebooting Yo" & _
                                "ur Machine" & vbLf & "Then Try To Change Resolution In Safe Mode.", "Information", MessageBoxButton.OK)
                            Exit Select
                        Case Else
                            MsgBox("Description: Failed To Change The Resolution.", "Information", MessageBoxButton.OK)
                            Exit Select
                    End Select
                End If
            End If
        End Sub
    End Class
End Namespace