private void _RestoreGlassFrame()
        {
            Assert.IsNull(_chromeInfo);
            Assert.IsNotNull(_window);

            // Expect that this might be called on OSes other than Vista
            // and if the window hasn't yet been shown, then we don't need to undo anything.
            if (!Utility.IsOSVistaOrNewer || _hwnd == IntPtr.Zero)
            {
                return;
            }

            _hwndSource.CompositionTarget.BackgroundColor = SystemColors.WindowColor;

            if (NativeMethods.DwmIsCompositionEnabled())
            {
                // If glass is enabled, push it back to the normal bounds.
                var dwmMargin = new MARGINS();
                NativeMethods.DwmExtendFrameIntoClientArea(_hwnd, ref dwmMargin);
            }
        }
 public static extern void DwmExtendFrameIntoClientArea(IntPtr hwnd, ref MARGINS pMarInset);
        private void _ExtendGlassFrame()
        {
            Assert.IsNotNull(_window);

            // Expect that this might be called on OSes other than Vista.
            if (!Utility.IsOSVistaOrNewer)
            {
                // Not an error.  Just not on Vista so we're not going to get glass.
                return;
            }

            if (IntPtr.Zero == _hwnd)
            {
                // Can't do anything with this call until the Window has been shown.
                return;
            }

            // Ensure standard HWND background painting when DWM isn't enabled.
            if (!NativeMethods.DwmIsCompositionEnabled())
            {
                _hwndSource.CompositionTarget.BackgroundColor = SystemColors.WindowColor;
            }
            else
            {
                // This makes the glass visible at a Win32 level so long as nothing else is covering it.
                // The Window's Background needs to be changed independent of this.

                // Apply the transparent background to the HWND
                _hwndSource.CompositionTarget.BackgroundColor = Colors.Transparent;

                // Thickness is going to be DIPs, need to convert to system coordinates.
                Thickness deviceGlassThickness = DpiHelper.LogicalThicknessToDevice(_chromeInfo.GlassFrameThickness);

                if (_chromeInfo.SacrificialEdge != SacrificialEdge.None)
                {
                    Thickness windowResizeBorderThicknessDevice = DpiHelper.LogicalThicknessToDevice(SystemParameters2.Current.WindowResizeBorderThickness);
                    if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Top))
                    {
                        deviceGlassThickness.Top -= windowResizeBorderThicknessDevice.Top;
                        deviceGlassThickness.Top = Math.Max(0, deviceGlassThickness.Top);
                    }
                    if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Left))
                    {
                        deviceGlassThickness.Left -= windowResizeBorderThicknessDevice.Left;
                        deviceGlassThickness.Left = Math.Max(0, deviceGlassThickness.Left);
                    }
                    if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Bottom))
                    {
                        deviceGlassThickness.Bottom -= windowResizeBorderThicknessDevice.Bottom;
                        deviceGlassThickness.Bottom = Math.Max(0, deviceGlassThickness.Bottom);
                    }
                    if (Utility.IsFlagSet((int)_chromeInfo.SacrificialEdge, (int)SacrificialEdge.Right))
                    {
                        deviceGlassThickness.Right -= windowResizeBorderThicknessDevice.Right;
                        deviceGlassThickness.Right = Math.Max(0, deviceGlassThickness.Right);
                    }
                }

                var dwmMargin = new MARGINS
                {
                    // err on the side of pushing in glass an extra pixel.
                    cxLeftWidth = (int)Math.Ceiling(deviceGlassThickness.Left),
                    cxRightWidth = (int)Math.Ceiling(deviceGlassThickness.Right),
                    cyTopHeight = (int)Math.Ceiling(deviceGlassThickness.Top),
                    cyBottomHeight = (int)Math.Ceiling(deviceGlassThickness.Bottom),
                };

                NativeMethods.DwmExtendFrameIntoClientArea(_hwnd, ref dwmMargin);
            }
        }
        private static bool _ExtendGlassFrameInternal(Window window, Thickness margin)
        {
            Assert.IsNotNull(window);
            Assert.IsTrue(window.CheckAccess());

            // Expect that this might be called on OSes other than Vista.
            if (!Utility.IsOSVistaOrNewer)
            {
                // Not an error.  Just not on Vista so we're not going to get glass.
                return false;
            }

            IntPtr hwnd = new WindowInteropHelper(window).Handle;
            if (IntPtr.Zero == hwnd)
            {
                throw new InvalidOperationException("Window must be shown before extending glass.");
            }

            HwndSource hwndSource = HwndSource.FromHwnd(hwnd);

            bool isGlassEnabled = NativeMethods.DwmIsCompositionEnabled();

            if (!isGlassEnabled)
            {
                window.Background = SystemColors.WindowBrush;
                hwndSource.CompositionTarget.BackgroundColor = SystemColors.WindowColor;
            }
            else
            {
                // Apply the transparent background to both the Window and the HWND
                window.Background = Brushes.Transparent;
                hwndSource.CompositionTarget.BackgroundColor = Colors.Transparent;

                // Thickness is going to be DIPs, need to convert to system coordinates.
                Point deviceTopLeft = DpiHelper.LogicalPixelsToDevice(new Point(margin.Left, margin.Top));
                Point deviceBottomRight = DpiHelper.LogicalPixelsToDevice(new Point(margin.Right, margin.Bottom));

                var dwmMargin = new MARGINS
                {
                    // err on the side of pushing in glass an extra pixel.
                    cxLeftWidth = (int)Math.Ceiling(deviceTopLeft.X),
                    cxRightWidth = (int)Math.Ceiling(deviceBottomRight.X),
                    cyTopHeight = (int)Math.Ceiling(deviceTopLeft.Y),
                    cyBottomHeight = (int)Math.Ceiling(deviceBottomRight.Y),
                };

                NativeMethods.DwmExtendFrameIntoClientArea(hwnd, ref dwmMargin);
            }

            // Even if glass isn't currently enabled, add the hook so we can appropriately respond
            // if that changes.

            bool addHook = !_extendedWindows.ContainsKey(hwnd);

            if (addHook)
            {
                HwndSourceHook hook = delegate(IntPtr innerHwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
                {
                    if (WM.DWMCOMPOSITIONCHANGED == (WM)msg)
                    {
                        _ExtendGlassFrameInternal(window, margin);
                        handled = false;
                    }
                    return IntPtr.Zero;
                };

                _extendedWindows.Add(hwnd, hook);
                hwndSource.AddHook(hook);
                window.Closing += _OnExtendedWindowClosing;
            }

            return isGlassEnabled;
        }