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WPF C# MoveWindow issue under Windows 11

I have an application with at least 2 separate windows.
The secondary window is too far from the PC to use the mouse, so I have a method that temporarily brings that specific window to the current main display, changes are done, then the window is sent back.
This worked well under Windows 10, however under Windows 11, the window seems to disappear and is nowhere to be seen during the initial call. It can however be sent back (from wherever it was hiding) to the secondary monitor.
Here is some code to position the window (normal MoveWindow):
// Position is assigned in the constructor of the second window
public System.Drawing.Rectangle Position { get; set; }
[DllImport("user32.dll", SetLastError = true)]
private static extern bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);
protected override void OnSourceInitialized(EventArgs e)
{
base.OnSourceInitialized(e);
MoveW();
}
public void MoveW()
{
WindowInteropHelper wih = new(this);
IntPtr hWnd = wih.Handle;
if (!Position.IsEmpty)
{
_ = MoveWindow(hWnd, Position.Left, Position.Top, Position.Width, Position.Height, false);
}
}
and here is how I am bringing the window to the current display (work perfect Win10):
// Getting the coordinates of the MainWindow
var screen = System.Windows.Forms.Screen.FromHandle(new WindowInteropHelper(App.Current.MainWindow).Handle);
System.Drawing.Rectangle rect = screen.WorkingArea;
// Simply passing them to second window needing to be moved
if (!rect.IsEmpty)
{
var wih = new WindowInteropHelper(this);
IntPtr hWnd = wih.Handle;
MoveWindow(hWnd, rect.Left, rect.Top, rect.Width, rect.Height, false);
}
Here is the link for MoveWindow
I have created a small GitHub project to illustrate the issue. If you have 2 screens and win10 and 11, get it from here.
Any suggestions?

As far as I noticed, on Windows 11, WindowState.Maximized seems to prevent the window from being shown after its location is changed by MoveWindow function.
So the workround is returing to WindowState.Normal before calling MoveWindow. It would be something like below.
WindowState state = this.WindowState;
try
{
this.WindowState = WindowState.Normal;
MoveWindow(hWnd, rect.Left, rect.Top, rect.Width, rect.Height, false);
}
finally
{
this.WindowState = state;
}

Is there a way to make a winforms window allways on bottom? [duplicate]

Some background
One of my current clients runs a chain of Internet points where customers an access the net through PC:s set up as "kiosks" (a custom-built application "locks" the computer until a user has signed in, and the running account is heavily restricted through the Windows group policy). Currently, each computer is running Windows XP and uses Active Desktop to display advertisements in the background. However, since my client has got problems with Active Desktop crashing on a daily basis (in addition to generally slowing down the computer) I have been asked to develop an application that replaces it.
The problem
I am trying to investigate whether it is possible to build a Windows forms application (using C#) that always stays in the background. The application should lie above the desktop (so that it covers any icons, files etc) but always behind all other running applications. I guess I'm really looking for a BottomMost property of the Form class (which doesn't exist, of course).
Any tips or pointers on how to achieve this would be highly appreciated.

This isn't directly supported by the .NET Form class, so you have two options:
1) Use the Win32 API SetWindowPos function.
pinvoke.net shows how to declare this for use in C#:
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);
const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOACTIVATE = 0x0010;
So in your code, call:
SetWindowPos(Handle, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE);
As you commented, this moves the form to the bottom of the z-order but doesn't keep it there. The only workaround I can see for this is to call SetWindowPos from the Form_Load and Form_Activate events. If your application is maximized and the user is unable to move or minimise the form then you might get away with this approach, but it's still something of a hack. Also the user might see a slight "flicker" if the form gets brought to the front of the z-order before the SetWindowPos call gets made.
2) subclass the form, override the WndProc function and intercept the WM_WINDOWPOSCHANGING Windows message, setting the SWP_NOZORDER flag (taken from this page).

I think the best way to do so is using the activated event handler and SendToBack method, like so:
private void Form1_Activated(object sender, EventArgs e)
{
this.SendToBack();
}

Set your window to be a child window of the desktop (the "Program Manager" or "progman" process). I've succeeded with this method in Windows XP (x86) and Windows Vista (x64).
I stumbled on this method while searching for a way to make a screensaver display as if it were wallpaper. It turns out, this is sort of built in to the system's .scr handler. You use screensaver.scr /p PID, where PID is the process id of another program to attach to. So write a program to find progman's handle, then invoke the .scr with that as the /p argument, and you have screensaver wallpaper!
The project I'm playing with now is desktop status display (shows the time, some tasks, mounted disks, etc), and it's built on Strawberry Perl and plain Win32 APIS (mainly the Win32::GUI and Win32::API modules), so the code is easy to port to or understand any dynamic language with similar Win32 API bindings or access to Windows' Scripting Host (eg, ActivePerl, Python, JScript, VBScript). Here's a relevant portion of the class that produces the window:
do { Win32::API->Import(#$_) or die "Win32::API can't import #$_ ($^E)" } for
[user32 => 'HWND FindWindow(LPCTSTR lpClassName, LPCTSTR lpWindowName)'],
[user32 => 'HWND SetParent(HWND hWndChild, HWND hWndNewParent)'],
sub __screen_x {
Win32::GUI::GetSystemMetrics(SM_CXSCREEN)
}
sub __screen_y {
Win32::GUI::GetSystemMetrics(SM_CYSCREEN)
}
sub _create_window { # create window that covers desktop
my $self = shift;
my $wnd = $$self{_wnd} = Win32::GUI::Window->new(
-width => __screen_x(), -left => 0,
-height => __screen_y(), -top => 0,
) or die "can't create window ($^E)";
$wnd->SetWindowLong(GWL_STYLE,
WS_VISIBLE
| WS_POPUP # popup: no caption or border
);
$wnd->SetWindowLong(GWL_EXSTYLE,
WS_EX_NOACTIVATE # noactivate: doesn't activate when clicked
| WS_EX_NOPARENTNOTIFY # noparentnotify: doesn't notify parent window when created or destroyed
| WS_EX_TOOLWINDOW # toolwindow: hide from taskbar
);
SetParent($$wnd{-handle}, # pin window to desktop (bottommost)
(FindWindow('Progman', 'Program Manager') or die "can't find desktop window ($^E)")
) or die "can't pin to desktop ($^E)";
Win32::GUI::DoEvents; # allow sizing and styling to take effect (otherwise DC bitmaps are the wrong size)
}
This program buffers output to prevent flickering, which you'll probably want to do as well. I create a DC (device context) and PaintDesktop to it (you could use any bitmap with only a couple more lines -- CreateCompatibleBitmap, read in a file, and select the bitmap's handle as a brush), then create a holding buffer to keep a clean copy of that background and a working buffer to assemble the pieces -- on each loop, copy in background, then draw lines and brush bitmaps and use TextOut -- which is then copied to the original DC, at which time it appears on screen.

Yes, function SetWindowPos with flag HWND_BOTTOM should help you. But, from my experience: even after calling SetWindowPos as result of some user operations your window may bring to front.

subclass the form, override the WndProc function and intercept the Windows message(s) that are responsible for moving it up the z-order when it gets activated.

Create a Panel that cover your form, but what ever you want on that Panel, then in the Panel's Click-Event write this.sendback .

I've managed to get rid of the flickering when using setwindowpos...
const UInt32 SWP_NOSIZE = 0x0001;
const UInt32 SWP_NOMOVE = 0x0002;
const UInt32 SWP_NOACTIVATE = 0x0010;
const UInt32 SWP_NOZORDER = 0x0004;
const int WM_ACTIVATEAPP = 0x001C;
const int WM_ACTIVATE = 0x0006;
const int WM_SETFOCUS = 0x0007;
static readonly IntPtr HWND_BOTTOM = new IntPtr(1);
const int WM_WINDOWPOSCHANGING = 0x0046;
[DllImport("user32.dll")]
static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X,
int Y, int cx, int cy, uint uFlags);
[DllImport("user32.dll")]
static extern IntPtr DeferWindowPos(IntPtr hWinPosInfo, IntPtr hWnd,
IntPtr hWndInsertAfter, int x, int y, int cx, int cy, uint uFlags);
[DllImport("user32.dll")]
static extern IntPtr BeginDeferWindowPos(int nNumWindows);
[DllImport("user32.dll")]
static extern bool EndDeferWindowPos(IntPtr hWinPosInfo);
private void Window_Loaded(object sender, RoutedEventArgs e)
{
IntPtr hWnd = new WindowInteropHelper(this).Handle;
SetWindowPos(hWnd, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
IntPtr windowHandle = (new WindowInteropHelper(this)).Handle;
HwndSource src = HwndSource.FromHwnd(windowHandle);
src.AddHook(new HwndSourceHook(WndProc));
}
private IntPtr WndProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
if (msg == WM_SETFOCUS)
{
IntPtr hWnd = new WindowInteropHelper(this).Handle;
SetWindowPos(hWnd, HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
handled = true;
}
return IntPtr.Zero;
}
private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
IntPtr windowHandle = (new WindowInteropHelper(this)).Handle;
HwndSource src = HwndSource.FromHwnd(windowHandle);
src.RemoveHook(new HwndSourceHook(this.WndProc));
}

Windows screensaver in C# using WPF crashing during preview mode

I have just started to learn C# and am trying to write a screensaver. My App.xaml.cs contains the following code for when the /p argument is used:
else if (arg1 == "/p")
{
if (e.Args[1] == null)
{
System.Windows.Forms.MessageBox.Show("Invalid or missing window handle.");
System.Windows.Application.Current.Shutdown();
}
IntPtr previewHandle = new IntPtr(long.Parse(e.Args[1]));
System.Windows.Application.Current.Run(new MainWindow(previewHandle));
}
Then in my MainWindow.xaml.cs, this construct handles the preview call:
public MainWindow(IntPtr previewHandle)
{
App.Current.Properties["isPreviewMode"] = true;
App.Current.Properties["previewHandle"] = previewHandle;
InitializeComponent();
}
After this, it crashes. In my MainWindow.xaml I have Loaded="MainWindow_Loaded".
In MainWindows.xaml.cs this is MainWindow_Loaded:
private void MainWindow_Loaded(object sender, RoutedEventArgs e)
{
if ((bool)App.Current.Properties["isPreviewMode"])
{
IntPtr myHandle = new WindowInteropHelper(this).Handle;
SetParent(myHandle, (IntPtr)App.Current.Properties["previewHandle"]);
SetWindowLong(myHandle, -16, new IntPtr(GetWindowLong(myHandle, -16) | 0x40000000));
Rectangle ParentRect;
GetClientRect((IntPtr)App.Current.Properties["previewHandle"], out ParentRect);
this.Top = ParentRect.X;
this.Left = ParentRect.Y;
this.Height = ParentRect.Height;
this.Width = ParentRect.Width;
}
ssimage.Source = new BitmapImage(new Uri("pack://application:,,,/Resources/EmbeddedImage.PNG"));
}
[DllImport("user32.dll")]
static extern IntPtr SetParent(IntPtr hWndChild, IntPtr hWndNewParent);
[DllImport("user32.dll")]
static extern int SetWindowLong(IntPtr hWnd, int nIndex, IntPtr dwNewLong);
[DllImport("user32.dll", SetLastError = true)]
static extern int GetWindowLong(IntPtr hWnd, int nIndex);
[DllImport("user32.dll")]
static extern bool GetClientRect(IntPtr hWnd, out Rectangle lpRect);
I have other code in the App.xaml.cs to handle changing the images on a timer and other code in MainWindow.xaml.cs to handle mouse movement, clicks and keypresses. Everything works fine when running the screensaver normally. It is just the preview that fails. What am I doing wrong?

To my knowledge, WPF does not allow you to retarget the window handle, so performing screensaver previews in WPF using your technique is impossible.
However, there is a workaround: if you configure WPF to render to a bitmap target (see RenderTargetBitmap), you could then blit that bitmap onto the desired destination window handle - but this would involve an unholy mix of GDI and WPF and probably have awful runtime performance; I doubt it would be worth the effort.

What I ended up doing was using the WPF windows to display when the screensaver runs normally in full screen with /s. I created a new regular windows form previewForm.cs with a picturebox to use for the preview. That works fine and there is no performance issues. I assume the picturebox is using GDI.
This is my modified App.xaml.cs for handling the /p argument:
else if (arg1 == "/p")
{
if (e.Args[1] == null)
{
System.Windows.Forms.MessageBox.Show("Invalid or missing window handle.");
System.Windows.Application.Current.Shutdown();
}
IntPtr previewHandle = new IntPtr(long.Parse(e.Args[1]));
pw = new previewForm(previewHandle);
GetImages();
pw.Show();
}
and my previewForm.cs construct to handle the preview:
public previewForm(IntPtr previewHandle)
{
InitializeComponent();
IntPtr myHandle = this.Handle;
SetParent(myHandle, previewHandle);
SetWindowLong(myHandle, -16, new IntPtr(GetWindowLong(myHandle, -16) | 0x40000000));
Rectangle ParentRect;
GetClientRect(previewHandle, out ParentRect);
this.Size = ParentRect.Size;
this.pictureBox1.Size = ParentRect.Size;
this.Location = new Point(0, 0);
}
So I used a mix of a WPF form and a regular windows form to accomplish this. And the performance is fine. Only uses like 14-18MB of RAM and practically no CPU.

Set the position of the window of a program

I'm building a C# wpf application that runs on a windows 8 tablet, and I call the virtual keyboard in my application, like this :
Process.Start(Environment.GetFolderPath(Environment.SpecialFolder.System) + System.IO.Path.DirectorySeparatorChar + "osk.exe");
I would like to know if there is a way of setting the position of the keyboard window on my tablet when I open it first. Something like adding XY coordinates to Process.Start
Thanks

Manipulating the OSK window will require your process to be running elevated. (The OSK has certain privileges which means it can't be manipulated by processes which aren't elevated.) But if your app is running elevated, you should find the code below works.
Note that you need to find the OSK window after launching the OSK, rather than getting the MainWindowHandle from the Process object after calling Start(). Due to the way that the OSK starts up, you'll find the HasExited property on the Process object is true, and the MainWindowHandle is not available.
Thanks,
Guy
private void buttonLaunchOSK_Click(object sender, EventArgs e)
{
// Launch the OSK.
Process.Start(Environment.GetFolderPath(Environment.SpecialFolder.System) + System.IO.Path.DirectorySeparatorChar + "osk.exe");
// Wait a moment for the OSK window to be created.
Thread.Sleep(200);
// Find the OSK window.
IntPtr hwndOSK = Form1.FindWindow("OSKMainClass", null);
// Move and size the OSK window.
Form1.MoveWindow(hwndOSK, 0, 0, 800, 300, true);
}
[DllImport("user32.dll", SetLastError = true)]
public static extern IntPtr FindWindow(string className, string windowTitle);
[DllImport("user32.dll", SetLastError = true)]
internal static extern bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);

Lost Focus Windows Mobile

I created an application in C # to address some needs of an existing application in the enterprise. Recently we had to buy another application to support billing. These applications running is as follows:
1st Application-> 2 Application -> 3 Application
When I do "Process.Start" for the third application "it opens but after a few seconds it loses focus for the 1st Application. Anybody know how can I avoid this?

You need to know the window class and/or title and then can use FindWindow to get a window handle for the window:
[DllImport("coredll.dll", EntryPoint="FindWindowW", SetLastError=true)]
private static extern IntPtr FindWindowCE(string lpClassName, string lpWindowName);
Using the window handle you can change the window back to normal display using SetWindowPos:
[DllImport("user32.dll", SetLastError=true)]
[return: MarshalAs(UnmanagedType.Bool)]
private static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int x, int y, int cx, int cy, uint uFlags);
In example, if the window has a class name of "App 3"
...
IntPtr handle;
try
{
// Find the handle to the window with class name x
handle = FindWindowCE("App 3", null);
// If the handle is found then show the window
if (handle != IntPtr.Zero)
{
// show the window
SetWindowPos(handle, 0, 0, 0, 0, 0, SWP_SHOWWINDOW | SWP_NOSIZE);
}
}
catch
{
MessageBox.Show("Could not find window.");
}
To find the window's class and title, start the CE remote tool "CE Spy" (part of VS installation) when app 3 is started. Then browse thru the window list and look the app 3 window. Double click the entry in the list and you will get the class name and title of app 3.
Instead of the extra SetWindowPos you can also use the simple ShowWindow API:
[DllImport("coredll.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool ShowWindow(IntPtr hWnd, ShowWindowCommands nCmdShow);
enum ShowWindowCommands
{
Hide = 0,
Normal = 1,
ShowMinimized = 2,
Maximize = 3, // is this the right value?
ShowMaximized = 3,
ShowNoActivate = 4,
Show = 5,
Minimize = 6,
ShowMinNoActive = 7,
ShowNA = 8,
Restore = 9,
ShowDefault = 10,
ForceMinimize = 11
}
...
IntPtr handle;
try
{
// Find the handle to the window with class name x
handle = FindWindowCE("App 3", null);
// If the handle is found then show the window
if (handle != IntPtr.Zero)
{
// show the window
ShowWindow(handle, ShowWindowCommands.Normal);
}
}
catch
{
MessageBox.Show("Could not find window.");
}
For details about pinvoke of FindWindow and SetWindowPos see pinvoke.net and MSDN. Best book about Win32 programming is Charles Petzold's Programming Windows.
When you started the process you need the OS give some time to settle the app (let's say 1-3 seconds), before you change the window.