原则上，只改这一次，下一次开机会还原，但如果需重开机，才会Update Registry中的设定，并重开机。

　　如果要永久设定其设定值，请将

b = ChangeDisplaySettings(DevM, 0)

　　改成

b = ChangeDisplaySettings(DevM, CDS_UPDATEREGISTRY)

　　注：

　　DevM.dmBitsPerPel 便是设定颜色数，其实应说每个Pixel要多少Bits来显示

　　4 --> 16色
　　8 --> 256色
　　16 --> 65536色 以此类推

Option Explicit
Private Declare Function EnumDisplaySettings Lib "user32" Alias _
"EnumDisplaySettingsA" (ByVal lpszDeviceName As Long, _
ByVal iModeNum As Long, lpDevMode As Any) As Long

Private Declare Function ChangeDisplaySettings Lib "user32" Alias _
"ChangeDisplaySettingsA" (lpDevMode As Any, ByVal dwflags As Long) As Long
Private Declare Function ExitWindowsEx Lib "user32" (ByVal uFlags As Long, _
ByVal dwReserved As Long) As Long

Const EWX_REBOOT = 2 ’ 重开机
Const CCDEVICENAME = 32
Const CCFORMNAME = 32

Const DM_BITSPERPEL = &H40000
Const DISP_CHANGE_SUCCESSFUL = 0
Const DISP_CHANGE_RESTART = 1
Const CDS_UPDATEREGISTRY = 1
Private Type DEVMODE
dmDeviceName As String * CCDEVICENAME
dmSpecVersion As Integer
dmDriverVersion As Integer
dmSize As Integer
dmDriverExtra As Integer

dmFields As Long
dmOrientation As Integer
dmPaperSize As Integer
dmPaperLength As Integer
dmPaperWidth As Integer
dmScale As Integer
dmCopies As Integer
dmDefaultSource As Integer
dmPrintQuality As Integer
dmColor As Integer
dmDuplex As Integer
dmYResolution As Integer
dmTTOption As Integer
dmCollate As Integer

dmFormName As String * CCFORMNAME
dmUnusedPadding As Integer
dmBitsPerPel As Integer
dmPelsWidth As Long
dmPelsHeight As Long
dmDisplayFlags As Long
dmDisplayFrequency As Long
End Type
Private DevM As DEVMODE
Private Sub Command1_Click()
Dim a As Boolean
Dim i As Long
Dim b As Long
Dim ans As Long
a = EnumDisplaySettings(0, 0, DevM) ’Initial Setting
DevM.dmBitsPerPel = 8 ’设定成256色
DevM.dmFields = DM_BITSPERPEL
b = ChangeDisplaySettings(DevM, 0)
If b = DISP_CHANGE_RESTART Then
　ans = MsgBox("要重开机设定才能完成，重开？", vbOKCancel)
　If ans = 1 Then
　　b = ChangeDisplaySettings(DevM, CDS_UPDATEREGISTRY)
　　Call ExitWindowsEx(EWX_REBOOT, 0)
　End If
Else
　If b <> DISP_CHANGE_SUCCESSFUL Then
　　Call MsgBox("设定有误", vbCritical)
　End If
End If
End Sub