Hide a WPF form from Alt+Tab

Question

I am wanting to hide a WPF window that has WindowStyle="None" , AllowTransparency="True" and ShowInTaskbar="False" from the task menu (Alt+Tab).

I have already researched this but all the results appear to be for WinForms or don't have an answer. Here are some of the sources I have already looked into:

Here is my XAML code:

<Window x:Class="DesktopInfo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:DesktopInfo"
        mc:Ignorable="d"
        Title="MainWindow" SizeToContent="WidthAndHeight" WindowStyle="None" AllowsTransparency="True"  Background="Transparent" ShowInTaskbar="False" Loaded="FormLoaded">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="Auto"/>
        </Grid.RowDefinitions>
        <TextBlock Text="Testing" Name="UsernameTextBlock" FontSize="20" FontWeight="Bold" Foreground="White"/>
        <TextBlock Name="ComputernameTextBlock" Grid.Row="1" FontSize="20" FontWeight="Bold" Foreground="White"/>
    </Grid>
</Window>

Here is my C# code:

using System;
using System.Windows;
using System.Windows.Forms;

namespace DesktopInfo
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    /// 
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }
}

No matter what I try, I cannot get the WPF form to not show up in the Alt+Tab menu. Any help is very much appreciated :)

UPDATE AFTER DUPLICATE FLAG After looking at the link that was provided (and previously viewed before asking this question), I would like to state that I, in fact, found the answer here and will post my full code as an answer to this question :)

[What about this?](https://stackoverflow.com/questions/23672595/how-to-hide-winform-or-wpf-application-from-alttab-and-from-task-managers-ap/23672596) — ProgrammingLlama, Jun 18 '19 at 08:56
@John Thank you for the link, I will update my question with why this doesn't fit my requirements :) — I.T Delinquent, Jun 18 '19 at 08:58
Did you try this https://stackoverflow.com/questions/357076/best-way-to-hide-a-window-from-the-alt-tab-program-switcher — Andy, Jun 18 '19 at 09:16
@Andy I actually saw this and it looked promising. Some of the comments on the answer state that it no longer works, however. It looks like a lot of work and to be honest I'm not sure where the code should go. — I.T Delinquent, Jun 18 '19 at 09:24
Possible duplicate of [Best way to hide a window from the Alt-Tab program switcher?](https://stackoverflow.com/questions/357076/best-way-to-hide-a-window-from-the-alt-tab-program-switcher) — Flater, Jun 18 '19 at 11:17

score 13 · Accepted Answer · edited Aug 13 '20 at 13:16

My final code following the answer from this StackOverflow question can be seen below:

using System;
using System.Windows;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Windows.Interop;

namespace DesktopInfo
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    /// 
    public partial class MainWindow : Window
    {

        [DllImport("user32.dll", SetLastError = true)]
        static extern int GetWindowLong(IntPtr hWnd, int nIndex);
        [DllImport("user32.dll")]
        static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);
        private const int GWL_EX_STYLE = -20;
        private const int WS_EX_APPWINDOW = 0x00040000, WS_EX_TOOLWINDOW = 0x00000080;

        public MainWindow() => InitializeComponent();
        
        //Form loaded event handler
        void FormLoaded(object sender, RoutedEventArgs args)
        {
            //Variable to hold the handle for the form
            var helper = new WindowInteropHelper(this).Handle;
            //Performing some magic to hide the form from Alt+Tab
            SetWindowLong(helper, GWL_EX_STYLE, (GetWindowLong(helper, GWL_EX_STYLE) | WS_EX_TOOLWINDOW) & ~WS_EX_APPWINDOW);
            
        }
    }
}

My form now runs as a background task, is still visible and cannot be seen in the Alt+Tab menu. Thank you, everyone, for your help :) I'm a little ashamed I didn't find the winning link before posting the question.

Hide a WPF form from Alt+Tab

1 Answers1

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