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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));
}

Determine if a window is topmost or not

I am able to set a windows position as topmost and also setting it no topmost with SetWindowPos. But i can't figure out how to check if a window is topmost or not. Is there any Method to check if a window is topmost or not with pinvoke?

You can use the GetWindowLong() function to check the Extended Window Styles.
Untested, but I believe it should work:
[DllImport("user32.dll", SetLastError=true)]
static extern int GetWindowLong(IntPtr hWnd, int nIndex);
const int GWL_EXSTYLE = -20;
const int WS_EX_TOPMOST = 0x0008;
public static bool IsWindowTopMost(IntPtr hWnd)
{
int exStyle = GetWindowLong(hWnd, GWL_EXSTYLE);
return (exStyle & WS_EX_TOPMOST) == WS_EX_TOPMOST;
}

Depending on the UI technology you*re using, you can choose of the following two:
Windows Forms: Form.TopMost
WPF: Window.TopMost
You can you those properties to check if a certain window is topmost and you can also use these to set a window topmost. I'd prefer these in favor of any win32 methods.

How to keep border on a fixed form?

I want my Windows Forms form to keep the window border, while having no title bar and being non-resizable (fixed) (similarly to window previews, when one hovers mouse over button on the taskbar):
Setting ControlBox to false and Text to "" removes the title bar and keeps the border as I want to, but the border is visible only if the form is sizeable. When I set the FormBorderStyle to one of the Fixed* styles, the border disappears:
How may I achieve the described behavior?

You can pinvoke SetWindowsLong and adjust window styles:
// run in LINQpad
private const int GWL_STYLE = -16;
private const int WS_SIZEBOX = 0x040000;
[DllImport("user32.dll", SetLastError = true)]
private static extern int GetWindowLong(IntPtr hWnd, int nIndex);
[DllImport("user32.dll")]
private static extern int SetWindowLong(IntPtr hWnd, int nIndex, int dwNewLong);
void Main()
{
var form = new Form();
form.ControlBox = false;
form.FormBorderStyle = FormBorderStyle.FixedDialog;
form.Show();
SetWindowLong(form.Handle, GWL_STYLE, GetWindowLong(form.Handle, GWL_STYLE) | WS_SIZEBOX);
}
After that you would have to prevent resizing manually though.

I just played around with a project of mine and set FormBorderStyle to FixedSingle through the Design view, and the window seems to keep the border for Windows 8. I initially had text in the title, which was forcing the border to render. I removed the text and the border no longer rendered, so as a hacky solution I just input an empty string, by hitting backspace a few times. This made the border show up and remain fixed.

Problem positioning window when using SetParent()

I'm trying to set childForm as the child of the main Excel window using the SetParent API through PInvoke:
Form childForm = new MyForm();
IntPtr excelHandle = (IntPtr) excelApplication.Hwnd;
SetParent(childForm.Handle, excelHandle);
childForm.StartPosition = FormStartPosition.Manual;
childForm.Left = 0;
childForm.Top = 0;
As you can see above, my intention is also to position the child in the top left corner of Excel window. However, for some reason the childForm always ends up at some weird location.
What is it that I am doing wrong?

While all answers here suggest perfectly logical approaches, none of them worked for me. Then I tried MoveWindow. For some reason I don't understand, it did the job.
Here's the code:
[DllImport("user32.dll", SetLastError = true)]
internal static extern bool MoveWindow(IntPtr hWnd, int X, int Y, int nWidth, int nHeight, bool bRepaint);
...
Form childForm = new MyForm();
IntPtr excelHandle = (IntPtr) excelApplication.Hwnd;
SetParent(childForm.Handle, excelHandle);
MoveWindow(childForm.Handle, 0, 0, childForm.Width, childForm.Height, true);

When using SetParent on a form that is currently a child of the desktop (in other words, one without a parent
set), you must set the WS_CHILD style and remove the WS_POPUP style. (See the Remarks section of the MSDN entry.) Windows requires that all owned windows have the WS_CHILD style set. This could also be causing the left and top properties to report/set the wrong values because the form doesn't know who it's daddy is. You can fix this by calling SetWindowLong after SetParent, but before you try to set the location:
//Remove WS_POPUP style and add WS_CHILD style
const UInt32 WS_POPUP = 0x80000000;
const UInt32 WS_CHILD = 0x40000000;
int style = GetWindowLong(this.Handle, GWL_STYLE);
style = (style & ~(WS_POPUP)) | WS_CHILD;
SetWindowLong(this.Handle, GWL_STYLE, style);

It depends on your ShowDialog call I believe. If you call ShowDialog without the parent paremeter, the parent is reset.
You could create a wrapper class that implements IWin32Window and returns the HWND to excel. Then you could pass that to the ShowDialog call of childForm.
You could also query the position of the excel application using GetWindowPos and then set the childForm accordingly.

Try a few things to diagnose the problem:
Put a breakpoint after setting Left
and Top, do Left and Top read zero?
Call SetParent last.
Make a method that sets Left and Top
again, and BeginInvoke the method.
Make sure your child window is really
the child. To do this call
ShowDialog, and try to click the
parent window. Make sure windows
prevents focus to the parent window.

Assuming you know how to get the hwnds of the windows you want to set z-order of, you can use this pInvoke:
public stati class WindowsApi
{
[DllImport("user32.dll")]
public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter,
int X, int Y, int cx, int cy, uint uFlags);
}
public class WindowZOrderPositioner
{
public void SetZOrder(IntPtr targetHwnd, IntPtr insertAfter)
{
IntPtr nextHwnd = IntPtr.Zero;
WindowsAPI.SetWindowPos(targetHwnd, insertAfter, 0, 0, 0, 0, SetWindowPosFlags.NoMove | SetWindowPosFlags.NoSize | SetWindowPosFlags.NoActivate);
}

Progress Bar in Setup Application

I have created a custom action for my setup project and have successfully implemented a form that displays a progress bar for a download step in my install (I'm using a WebClient in my custom action code). So I have two questions that relate to each other.
Is there any way to show a download progress bar in the main setup window rather than creating a separate form that I display as I have done? I would prefer this.
If not, then what can I do to cause my form to display in front of the actual setup window when I call form.ShowDialog()? I've also called BringToFront() on it which doesn't work either. It's there, but it's always behind the main setup window. Seems there has to be some way to get the correct z-order.
Thanks for your help.

So I gave up on the idea of integrating the progress bar into the actual installer screen, but it's just plain ridiculous what it takes to get the Windows Form to display on top. I have to get a handle to the installer Window and send it to the background because bringing the progress bar window forward simply won't work. I've moved to Mac development now so coming back to this is just frustrating. I remember thinking C# .NET was pretty cool. It's got NOTHING on Cocoa/Objective-C.
It's infuriating having a method called BringToFront() that simply ignores you. Why do I have to drop down to Windows API code to do something as fundamental to a GUI as managing the the Z-Order? Z-Order? Seriously?
In case you're wondering, here's what I ended up doing (via google):
[DllImport("user32.dll", EntryPoint = "SetWindowPos")]
public static extern bool SetWindowPos(
IntPtr hWnd, // window handle
IntPtr hWndInsertAfter, // placement-order handle
int X, // horizontal position
int Y, // vertical position
int cx, // width
int cy, // height
uint uFlags); // window positioning flags
public const uint SWP_NOSIZE = 0x1;
public const uint SWP_NOMOVE = 0x2;
public const uint SWP_SHOWWINDOW = 0x40;
public const uint SWP_NOACTIVATE = 0x10;
[DllImport("user32.dll", EntryPoint = "GetWindow")]
public static extern IntPtr GetWindow(
IntPtr hWnd,
uint wCmd);
public const uint GW_HWNDFIRST = 0;
public const uint GW_HWNDLAST = 1;
public const uint GW_HWNDNEXT = 2;
public const uint GW_HWNDPREV = 3;
public static void ControlSendToBack(IntPtr control)
{
bool s = SetWindowPos(
control,
GetWindow(control, GW_HWNDLAST),
0, 0, 0, 0,
SWP_NOSIZE | SWP_NOMOVE | SWP_NOACTIVATE);
}
I get a handle to the installer window and then call ControlSendToBack() on it. It works, but it sends it to the very back. I tried another method that would just send it back one position, but this wouldn't work either. Windows programming--as good as it was in 1995. Cool.

Another way of doing this is to use a BackgroundWorker. You let the Background Worker handle the downloading of the file so it doesn't prevent the UI being updated.
See this link on donnetperls