Question

How can I make a WPF window that will never appear in the Flip3d (Winkey+Tab) dialog?

Answer 1

Here is how I do it:

...
using System.Runtime.InteropServices;
using System.Windows.Interop;
namespace NoFlip3D
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        [DllImport("dwmapi.dll", PreserveSig = false)]
        public static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int attrValue, int attrSize);
        [Flags]
        public enum DwmWindowAttribute
        {
            NCRenderingEnabled = 1,
            NCRenderingPolicy,
            TransitionsForceDisabled,
            AllowNCPaint,
            CaptionButtonBounds,
            NonClientRtlLayout,
            ForceIconicRepresentation,
            Flip3DPolicy,
            ExtendedFrameBounds,
            HasIconicBitmap,
            DisallowPeek,
            ExcludedFromPeek,
            Last
        }

        [Flags]
        public enum DwmNCRenderingPolicy
        {
            UseWindowStyle,
            Disabled,
            Enabled,
            Last
        }
        public MainWindow()
        {
            InitializeComponent();
        }
        public static void RemoveFromFlip3D(IntPtr Hwnd)
        {           
            int renderPolicy = (int)DwmNCRenderingPolicy.Enabled;
            DwmSetWindowAttribute(Hwnd, (int)DwmWindowAttribute.Flip3DPolicy, ref renderPolicy, sizeof(int));
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            IntPtr AppHandle = new WindowInteropHelper(this).Handle;
            RemoveFromFlip3D(AppHandle);
        }
    }
}

It hides from Flip3D and the other ones remain as they were (alt-tab and taskbar). However, the application remains showing in background while Flip3D is running.