dotnet 读 WPF 源代码笔记 ShowInTaskbar 的实现原理

        /// <summary>
        ///     Get or create the hidden window used for parenting when ShowInTaskbar == false.
        /// </summary>
        private HwndWrapper EnsureHiddenWindow()
        {
            if (_hiddenWindow == null)
            {
                _hiddenWindow = new HwndWrapper(
                    0, // classStyle
                    NativeMethods.WS_OVERLAPPEDWINDOW, // style
                    0, // exStyle
                    NativeMethods.CW_USEDEFAULT, // x
                    NativeMethods.CW_USEDEFAULT, // y
                    NativeMethods.CW_USEDEFAULT, // width
                    NativeMethods.CW_USEDEFAULT, // height
                    "Hidden Window", // name
                    IntPtr.Zero,
                    null
                );
            }

            return _hiddenWindow;
        }

        /// <summary>
        ///     The DependencyProperty for ShowInTaskbarProperty.
        ///     Flags:              None
        ///     Default Value:      true
        /// </summary>
        public static readonly DependencyProperty ShowInTaskbarProperty =
                DependencyProperty.Register("ShowInTaskbar",
                        typeof(bool),
                        typeof(Window),
                        new FrameworkPropertyMetadata(BooleanBoxes.TrueBox,
                                new PropertyChangedCallback(_OnShowInTaskbarChanged),
                                new CoerceValueCallback(VerifyAccessCoercion)));

        private static void _OnShowInTaskbarChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            Window w = (Window)d;

            Debug.Assert(w != null, "DependencyObject must be of type Window.");
            w.OnShowInTaskbarChanged();
        }

        private void OnShowInTaskbarChanged()
        {
            ...
                    SetTaskbarStatus();
            ...
        }

        /// <summary>
        ///     sets taskbar status
        /// </summary>
        private void SetTaskbarStatus()
        {
            if (ShowInTaskbar == false) // don't show in taskbar
            {
                // To remove the taskbar button for this window it needs to have a non-null parent
                // (we'll create a hidden window for this purpose) and not have WS_EX_APPWINDOW

                // Create this now, even if we're not currently going to parent it.
                // If the Owner changes, we'll need to switch to this.
                EnsureHiddenWindow();

                // when this window is unowned
                if (_ownerHandle == IntPtr.Zero)
                {
                    SetOwnerHandle(_hiddenWindow.Handle);

                    ...
                }

                ...
            }
            else // (ShowInTaskbar == true) show in task bar
            {
                ...
            }
        }