Overlay windows is not coming on top when ShowInTaskbar="False" is set at window level and uiAccess="true"？

Question

I am developing one overlay application(WPF app in .net 6 in visual studio 2022) to make window to show on top of all the application.

Added app.Manifest file and made uiacceess=true app.manifest:

    <requestedExecutionLevel level="asInvoker" uiAccess="true" />

MainWindow.xaml:

<Window x:Class="WpfApp2.MainWindow"

        ...
        Title="MainWindow" Height="450" Width="800"  ShowInTaskbar="False"  >

If i remove the ShowInTaskbar = false setting from window level and build and sign the exe - at this time the exe is coming on top of all the apps .

Just want to understand why ShowInTaskbar = false(setting in window) property is not allowing the window to come on top of other application/games eventhough we made above changes?

Answer 1

You could try the workaround suggested here:

"When we set ShowInTaskbar=false on the Window, WPF is for some reason creating a hidden owner window that does not have WS_EX_TOPMOST set for its extended window style, regardless of whether our window has TopMost=true.

using System
using System.Windows.Interop;

public partial class SomeWindow
{
    public enum GetWindowCmd : uint
    {
        GW_HWNDFIRST = 0
        GW_HWNDLAST = 1
        GW_HWNDNEXT = 2
        GW_HWNDPREV = 3,
        GW_OWNER = 4,
        GW_CHILD = 5,
        GW_ENABLEDPOPUP = 6
    }

    [DllImport("user32.dll")]
    public static extern IntPtr GetWindow(IntPtr hWnd, GetWindowCmd uCmd);

    [Flags]
    public enum SetWindowPosFlags
    {
        SWP_NOSIZE = 0x0001,
        SWP_NOMOVE = 0x0002,
        SWP_NOZORDER = 0x0004,
        SWP_NOREDRAW = 0x0008,
        SWP_NOACTIVATE = 0x0010,
        SWP_FRAMECHANGED = 0x0020,
        SWP_SHOWWINDOW = 0x0040,
        SWP_HIDEWINDOW = 0x0080,
        SWP_NOCOPYBITS = 0x0100,
        SWP_NOOWNERZORDER = 0x0200,
        SWP_NOSENDCHANGING = 0x0400
    }

    [DllImport("user32.dll")]
    public static extern int SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int cx, int cy, SetWindowPosFlags uFlags);

    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        IntPtr hWnd = new WindowInteropHelper(this).Handle;

        IntPtr hWndHiddenOwner = GetWindow(hWnd, GetWindowCmd.GW_OWNER);

        if (hWndHiddenOwner != IntPtr.Zero)
        {
            IntPtr HWND_TOPMOST = new IntPtr(-1);
            SetWindowPos(hWndHiddenOwner, HWND_TOPMOST, 0, 0, 0, 0,
               SetWindowPosFlags.SWP_NOMOVE |
               SetWindowPosFlags.SWP_NOSIZE |
               SetWindowPosFlags.SWP_NOACTIVATE);
        }
    }
}