Private Const RDW_INVALIDATE As Integer = &H1
    <System.Runtime.InteropServices.DllImport("user32.dll", SetLastError:=True)> _
    Private Shared Function GetDesktopWindow() As IntPtr
    End Function
    <System.Runtime.InteropServices.DllImport("user32.dll", SetLastError:=True)> _
    Private Shared Function LockWindowUpdate(ByVal hwndLock As IntPtr) As Integer
    End Function
    <System.Runtime.InteropServices.DllImport("user32.dll", SetLastError:=True)> _
    Private Shared Function RedrawWindow(ByVal hwnd As IntPtr, ByVal lprcUpdate As Integer, ByVal hrgnUpdate As Integer, ByVal fuRedraw As Integer) As Integer
    End Function

    Public Sub RefreshDesktop()
        Dim hDesk As IntPtr = GetDesktopWindow()
        LockWindowUpdate(hDesk)
        RedrawWindow(hDesk, 0, 0, RDW_INVALIDATE)
        LockWindowUpdate(IntPtr.Zero)
    End Sub

Private Const RDW_INVALIDATE As Long = &H1
Private Declare Function GetDesktopWindow Lib "user32" () As Long
Private Declare Function LockWindowUpdate Lib "user32" (ByVal hwndLock As Long) As Long
Private Declare Function RedrawWindow Lib "user32" (ByVal hwnd As Long, lprcUpdate As Any, ByVal hrgnUpdate As Long, ByVal fuRedraw As Long) As  Long

Public Sub RefreshDesktop()
    Dim hDesk As Long
    hDesk = GetDesktopWindow
    Call LockWindowUpdate(hDesk)
    Call RedrawWindow(hDesk, ByVal 0&, ByVal 0&,  RDW_INVALIDATE)
    Call LockWindowUpdate(False)
End Sub

//using System;
//using System.Runtime.InteropServices;
private const uint RDW_INVALIDATE = 0x1U;
[DllImport("user32.dll", SetLastError = true)]
private static extern IntPtr GetDesktopWindow();
[DllImport("user32.dll", SetLastError = true)]
private static extern bool LockWindowUpdate(IntPtr hWndLock);
[DllImport("user32.dll", SetLastError = true)]
private static extern bool RedrawWindow(IntPtr hWnd, HandleRef lprcUpdate, HandleRef hrgnUpdate, uint flags);

public static void RefreshDesktop() {
  IntPtr hDesk = GetDesktopWindow();
  LockWindowUpdate(hDesk);
  RedrawWindow(hDesk, new HandleRef(null, IntPtr.Zero), new HandleRef(null, IntPtr.Zero), RDW_INVALIDATE);
  LockWindowUpdate(IntPtr.Zero);
}

procedure RefreshDesktop(const Carribou: boolean= false);
var DW : HWND;
begin
  if Carribou then
    SystemParametersInfo(SPI_SETDESKWALLPAPER, 0, Nil, SPIF_SENDCHANGE)
  else
  begin
    DW := windows.GetDesktopWindow;
    LockWindowUpdate(DW);
    RedrawWindow(DW, nil, 0, RDW_INVALIDATE);
    LockWindowUpdate(0);
  end;
end;