如何防止PowerPoint（Office 365 64位）窗口重新绘制？

Question

我有一个图形激烈的PowerPoint加载项，该加载项正在重新绘制屏幕。 I'm trying to lock the PowerPoint window from VBA while the changes are being made with the following code (64-bit Office):

Private Declare PtrSafe Function SendMessage Lib "user32" Alias "SendMessageA" _
    (ByVal hWnd As LongPtr, ByVal wMsg As Long, _
     ByVal wParam As LongPtr, Optional lParam As Any) As LongPtr
Public Const WM_SETREDRAW = &HB

Sub testLock()
    Static hWnd As LongPtr
    hWnd = FindWindow("PPTFrameClass")
    SendMessage hWnd, WM_SETREDRAW, False, 0&
End Sub

Sub testUnlock()
    Static hWnd As LongPtr
    hWnd = FindWindow("PPTFrameClass")
    SendMessage hWnd, WM_SETREDRAW, True, 0&
End Sub

When I do, this is the result (a mostly white window, with some stray lines):

What am I doing wrong?我也尝试了lockwindowupdate，但不能阻止更新。