• You create the window by using the CreateWindowEx function, and the dwExStyle parameter is set to WS_EX_LAYERED.
• The Win32 application calls the SetLayeredWindowAttributes function to set the opacity and transparency color key of the window.

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Steps to reproduce the behavior

1. Create a Visual C++ Win32 project in Microsoft Visual Studio .NET.
2. Create a main window by using the CreateWindowEx function. Set the dwExStyle parameter to WS_EX_LAYERED.
3. Call the SetLayeredWindowAttributes function. The code is similar to the following.

   BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
   {
   	HWND hWnd;
   	hInst = hInstance; // Store instance handle in our global variable
   	hWnd = CreateWindowEx(
   				WS_EX_LAYERED, // extended window style
   				szWindowClass, // registered class name
   				szTitle, // window name
   				WS_OVERLAPPEDWINDOW, // window style
   				CW_USEDEFAULT, // horizontal position of window
   				0, // vertical position of window
   				CW_USEDEFAULT, // window width
   				0, // window height
   				NULL, // handle to parent or owner window
   				NULL, // menu handle or child identifier
   				hInstance, // handle to application instance
   				NULL // window-creation data
   			);
   	if (!hWnd)
   	{
   	return FALSE;
   	}
   	SetLayeredWindowAttributes(hWnd,0,128,LWA_ALPHA);
   	ShowWindow(hWnd, nCmdShow);
   	UpdateWindow(hWnd);
   	return TRUE;
   }
   

4. On a computer that is running Microsoft Windows 2000 or Microsoft Windows XP, run the application that you created, and then run a DirectX application.
5. Move the window that you created in step 2 over the DirectX application. The images in the window flash.
   
   Note This behavior does not occur when you run Graphics Device Interface (GDI) applications that repeatedly paint images in procedures.

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