Replacing the windows desktop

Question

For a software project that I'm doing I kind of need te replace the desktop window.

The requirements:

The Window needs to be over the desktop icons (they are no longer needed)
Multiple screens/monitors
Other windows can run as usual
I'd like to keep the taskbar intact
When pressing windows+D or click the desktop button it should show my application.

I currently have been trying Naskohell, but this replaces the entire desktop including the taskbar. I could write my own taskbar, but I feel like this is a lot of extra work that i can hopefully avoid.

Then there is the SetWindowPos function, but I have no idea which Z level to use to achieve what I want.

Could anybody tell me what the best way is to achieve my requirements?

score 2 · Accepted Answer · edited May 23 '17 at 12:15

You need to be on top of desktop, below your apps, and hiding the taskbar. Id first try to hide the taskbar via Hide TaskBar in WinForms Application

Secondly, set your window to bottom most via using HWND_BOTTOM. There's some quirky behavior that's best to test across multiple OS's Setting a Windows form to be bottommost

EDIT - ok took a little fiddling because the taskbar keeps showing up. There will be a flicker when it loads, it then goes to the back. Some of this could be optimized, but I'll leave that to you - but here's a working demo. I've tested moving the taskbar and multiple desktops - all seems to work ok. You'll need to prevent the window from closing as well (if you want that behavior) but hooking into WM_CLOSE for ex. and ignoring it (still won't stop someone from using task manager, in that case you'd need something like a watcher process and both proceses watching each other to detect when the other is closed). I've compiled this from several SO posts and a bit of twiddling.

The window properties Show in taskbar = false WindowState = maximized ControlBox = false FormBorderStyle = none

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace DesktopReplacement
{
    public partial class Form1 : Form
    {
        private bool _enableOverride;
        internal class NativeMethods
        {
            public const int WM_WINDOWPOSCHANGING = 0x46;
            public const int WM_WINDOWPOSCHANGED = 0x47;
            public const int GWL_HWNDPARENT = -8;
            public const int SW_SHOW = 1;


            [Flags()]
            public enum SetWindowPosFlags
            {
                SWP_NOSIZE = 0x1,
                SWP_NOMOVE = 0x2,
                SWP_NOZORDER = 0x4,
                SWP_NOREDRAW = 0x8,
                SWP_NOACTIVATE = 0x10,
                SWP_FRAMECHANGED = 0x20,
                SWP_DRAWFRAME = SWP_FRAMECHANGED,
                SWP_SHOWWINDOW = 0x40,
                SWP_HIDEWINDOW = 0x80,
                SWP_NOCOPYBITS = 0x100,
                SWP_NOOWNERZORDER = 0x200,
                SWP_NOREPOSITION = SWP_NOOWNERZORDER,
                SWP_NOSENDCHANGING = 0x400,
                SWP_DEFERERASE = 0x2000,
                SWP_ASYNCWINDOWPOS = 0x4000,
            }

            public enum WindowZOrder
            {
                HWND_TOP = 0,
                HWND_BOTTOM = 1,
                HWND_TOPMOST = -1,
                HWND_NOTOPMOST = -2,
            }

            [StructLayout(LayoutKind.Sequential)]
            public struct WINDOWPOS
            {
                public IntPtr hWnd;
                public IntPtr hwndInsertAfter;
                public int x;
                public int y;
                public int cx;
                public int cy;
                public SetWindowPosFlags flags;

                // Returns the WINDOWPOS structure pointed to by the lParam parameter
                // of a WM_WINDOWPOSCHANGING or WM_WINDOWPOSCHANGED message.
                public static WINDOWPOS FromMessage(Message msg)
                {
                    // Marshal the lParam parameter to an WINDOWPOS structure,
                    // and return the new structure
                    return (WINDOWPOS)Marshal.PtrToStructure(msg.LParam, typeof(WINDOWPOS));
                }

                // Replaces the original WINDOWPOS structure pointed to by the lParam
                // parameter of a WM_WINDOWPOSCHANGING or WM_WINDOWPSCHANGING message
                // with this one, so that the native window will be able to see any
                // changes that we have made to its values.
                public void UpdateMessage(Message msg)
                {
                    // Marshal this updated structure back to lParam so the native
                    // window can respond to our changes.
                    // The old structure that it points to should be deleted, too.
                    Marshal.StructureToPtr(this, msg.LParam, true);
                }
            }
        }


        public static class HWND
        {
            public static readonly IntPtr
            NOTOPMOST = new IntPtr(-2),
            BROADCAST = new IntPtr(0xffff),
            TOPMOST = new IntPtr(-1),
            TOP = new IntPtr(0),
            BOTTOM = new IntPtr(1);
        }


        public static class SWP
        {
            public static readonly int
            NOSIZE = 0x0001,
            NOMOVE = 0x0002,
            NOZORDER = 0x0004,
            NOREDRAW = 0x0008,
            NOACTIVATE = 0x0010,
            DRAWFRAME = 0x0020,
            FRAMECHANGED = 0x0020,
            SHOWWINDOW = 0x0040,
            HIDEWINDOW = 0x0080,
            NOCOPYBITS = 0x0100,
            NOOWNERZORDER = 0x0200,
            NOREPOSITION = 0x0200,
            NOSENDCHANGING = 0x0400,
            DEFERERASE = 0x2000,
            ASYNCWINDOWPOS = 0x4000;
        }


        [DllImport("user32.dll", SetLastError = true)]
        static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

        [DllImport("user32.dll", SetLastError = true)]
        static extern IntPtr FindWindow(string lpWindowClass, string lpWindowName);

        [DllImport("user32.dll", SetLastError = true)]
        static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string className, string windowTitle);

        [DllImport("user32.dll")]
        public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, int uFlags);

        [DllImport("user32.dll")]
        private static extern int ShowWindow(IntPtr hwnd, int command);



        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {

            IntPtr hprog = FindWindowEx(
                FindWindowEx(
                    FindWindow("Progman", "Program Manager"),
                    IntPtr.Zero, "SHELLDLL_DefView", ""
                ),
                IntPtr.Zero, "SysListView32", "FolderView"
            );

            SetWindowLong(this.Handle, NativeMethods.GWL_HWNDPARENT, hprog);
        }

        protected override void WndProc(ref Message m)
        {
            if (_enableOverride)
            {
                if (m.Msg == NativeMethods.WM_WINDOWPOSCHANGING)
                {

                    // Extract the WINDOWPOS structure corresponding to this message
                    NativeMethods.WINDOWPOS wndPos = NativeMethods.WINDOWPOS.FromMessage(m);


                    wndPos.flags = wndPos.flags | NativeMethods.SetWindowPosFlags.SWP_NOZORDER;
                    wndPos.UpdateMessage(m);

                }
            }

            base.WndProc(ref m);
        }


        private void timer1_Tick(object sender, EventArgs e)
        {
            SetWindowPos(Handle, HWND.BOTTOM, 0, 0, 0, 0, SWP.SHOWWINDOW | SWP.NOMOVE | SWP.NOOWNERZORDER | SWP.NOSIZE | SWP.NOACTIVATE);

            IntPtr task = FindWindow("Shell_TrayWnd", "");
            ShowWindow(task, NativeMethods.SW_SHOW);

            _enableOverride = true;
        }

    }
}

Since you are using WPF - give this a try. It needs some cleanup/formatting but you get the point :)

using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;
using System.Windows.Threading;

namespace WpfApplication1
{
    /// 
    /// Interaction logic for MainWindow.xaml
    /// 
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            this.SourceInitialized += MainWindow_SourceInitialized;
            this.WindowStyle = WindowStyle.None;
            this.Loaded += Window_Loaded;
            this.WindowState = WindowState.Maximized;
            InitializeComponent();


            DispatcherTimer dispatcherTimer = new DispatcherTimer();
            dispatcherTimer.Tick += dispatcherTimer_Tick;
            dispatcherTimer.Interval = new TimeSpan(0, 0, 0, 0, 500);
            dispatcherTimer.Start();

        }


        private bool _enableOverride;
        internal class NativeMethods
        {
            public const int WM_WINDOWPOSCHANGING = 0x46;
            public const int WM_WINDOWPOSCHANGED = 0x47;
            public const int GWL_HWNDPARENT = -8;
            public const int SW_SHOW = 1;


            [Flags]
            public enum SetWindowPosFlags
            {
                SWP_NOSIZE = 0x1,
                SWP_NOMOVE = 0x2,
                SWP_NOZORDER = 0x4,
                SWP_NOREDRAW = 0x8,
                SWP_NOACTIVATE = 0x10,
                SWP_FRAMECHANGED = 0x20,
                SWP_DRAWFRAME = SWP_FRAMECHANGED,
                SWP_SHOWWINDOW = 0x40,
                SWP_HIDEWINDOW = 0x80,
                SWP_NOCOPYBITS = 0x100,
                SWP_NOOWNERZORDER = 0x200,
                SWP_NOREPOSITION = SWP_NOOWNERZORDER,
                SWP_NOSENDCHANGING = 0x400,
                SWP_DEFERERASE = 0x2000,
                SWP_ASYNCWINDOWPOS = 0x4000
            }

            public enum WindowZOrder
            {
                HWND_TOP = 0,
                HWND_BOTTOM = 1,
                HWND_TOPMOST = -1,
                HWND_NOTOPMOST = -2
            }

            [StructLayout(LayoutKind.Sequential)]
            public struct WINDOWPOS
            {
                public IntPtr hWnd;
                public IntPtr hwndInsertAfter;
                public int x;
                public int y;
                public int cx;
                public int cy;
                public SetWindowPosFlags flags;

                // Returns the WINDOWPOS structure pointed to by the lParam parameter
                // of a WM_WINDOWPOSCHANGING or WM_WINDOWPOSCHANGED message.
                public static WINDOWPOS FromMessage(IntPtr lParam)
                {
                    // Marshal the lParam parameter to an WINDOWPOS structure,
                    // and return the new structure
                    return (WINDOWPOS)Marshal.PtrToStructure(lParam, typeof(WINDOWPOS));
                }

                // Replaces the original WINDOWPOS structure pointed to by the lParam
                // parameter of a WM_WINDOWPOSCHANGING or WM_WINDOWPSCHANGING message
                // with this one, so that the native window will be able to see any
                // changes that we have made to its values.
                public void UpdateMessage(IntPtr lParam)
                {
                    // Marshal this updated structure back to lParam so the native
                    // window can respond to our changes.
                    // The old structure that it points to should be deleted, too.
                    Marshal.StructureToPtr(this, lParam, true);
                }
            }
        }


        public static class HWND
        {
            public static readonly IntPtr
            NOTOPMOST = new IntPtr(-2),
            BROADCAST = new IntPtr(0xffff),
            TOPMOST = new IntPtr(-1),
            TOP = new IntPtr(0),
            BOTTOM = new IntPtr(1);
        }


        public static class SWP
        {
            public static readonly int
            NOSIZE = 0x0001,
            NOMOVE = 0x0002,
            NOZORDER = 0x0004,
            NOREDRAW = 0x0008,
            NOACTIVATE = 0x0010,
            DRAWFRAME = 0x0020,
            FRAMECHANGED = 0x0020,
            SHOWWINDOW = 0x0040,
            HIDEWINDOW = 0x0080,
            NOCOPYBITS = 0x0100,
            NOOWNERZORDER = 0x0200,
            NOREPOSITION = 0x0200,
            NOSENDCHANGING = 0x0400,
            DEFERERASE = 0x2000,
            ASYNCWINDOWPOS = 0x4000;
        }


        [DllImport("user32.dll", SetLastError = true)]
        static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr dwNewLong);

        [DllImport("user32.dll", SetLastError = true)]
        static extern IntPtr FindWindow(string lpWindowClass, string lpWindowName);

        [DllImport("user32.dll", SetLastError = true)]
        static extern IntPtr FindWindowEx(IntPtr parentHandle, IntPtr childAfter, string className, string windowTitle);

        [DllImport("user32.dll")]
        public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, int uFlags);

        [DllImport("user32.dll")]
        private static extern int ShowWindow(IntPtr hwnd, int command);


        private void dispatcherTimer_Tick(object sender, EventArgs e)
        {
            //ensure we don't overlap the taskbar.
            SetWindowPos(new WindowInteropHelper(this).Handle, HWND.BOTTOM, 0, 0, 0, 0, SWP.SHOWWINDOW | SWP.NOMOVE | SWP.NOOWNERZORDER | SWP.NOSIZE | SWP.NOACTIVATE);

            IntPtr task = FindWindow("Shell_TrayWnd", "");
            ShowWindow(task, NativeMethods.SW_SHOW);

            _enableOverride = true;
        }


        private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
        {
            if (_enableOverride)
            {
                if (msg == NativeMethods.WM_WINDOWPOSCHANGING)
                {
                    Debug.WriteLine("WM_WINDOWPOSCHANGING");
                    // Extract the WINDOWPOS structure corresponding to this message
                    //lParam has the ptr to a WindowsPos structure if its our WM_WINDOWPOSCHANGING struct
                    NativeMethods.WINDOWPOS wndPos = NativeMethods.WINDOWPOS.FromMessage(lParam);

                    wndPos.flags = wndPos.flags | NativeMethods.SetWindowPosFlags.SWP_NOZORDER;
                    wndPos.UpdateMessage(lParam);
                    //handled = true;
                }
            }

            return IntPtr.Zero;
        }

        private void MainWindow_SourceInitialized(object sender, EventArgs e)
        {
            HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
            source.AddHook(WndProc);
        }

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

            IntPtr hprog = FindWindowEx(
                           FindWindowEx(
                               FindWindow("Progman", "Program Manager"),
                               IntPtr.Zero, "SHELLDLL_DefView", ""
                           ),
                           IntPtr.Zero, "SysListView32", "FolderView"
                       );

            SetWindowLong(hWnd, NativeMethods.GWL_HWNDPARENT, hprog);
        }
    }
}

But I actually want the taskbar to be visible.. So I guess I'll just leave that out. — Dylan Snel, Jan 14 '16 at 09:24
email me a basic reproduction you are having probs with I can try to check it out - where are you running into issues? adamt at microsoft — Adam Tuliper, Jan 18 '16 at 21:13

Replacing the windows desktop

1 Answers1