How to show form in front in C#

Question

Folks,

Please does anyone know how to show a Form from an otherwise invisible application, and have it get the focus (i.e. appear on top of other windows)?

Answer 1

1. You said that it works fine when you use Application.Run. Why don't you want to use Application.Run, then?
2. Have you tried calling BringToFront() from OnLoad or OnShown?

Answer 2

I've hacked this from an application I've been working on. We have a large application that loads a series of modules written by different teams. We have written one of these modules, and needed to have a login dialog open during this initialization. It was set to '.TopMost=true', but that didn't work.

It uses the WindowsFormsSynchronizationContext to open a dialog box, and then get the result of the dialog box back.

I rarely do GUI coding, and suspect this may be overkill, but it might help someone if they get stuck. I had problems with understanding how state is passed to the SendOrPostCallback, as all the examples I could find didn't use it.

Also this is taken from a working application, but I've removed several bits of code, and changed some of the details. Apologies if it doesn't compile.

public bool Dummy()
{

// create the login dialog
DummyDialogForm myDialog = new DummyDialogForm();

// How we show it depends on where we are. We might be in the main thread, or in a background thread
// (There may be better ways of doing this??)
if (SynchronizationContext.Current == null)
{
    // We are in the main thread. Just display the dialog
    DialogResult result = myDialog.ShowDialog();
    return result == DialogResult.OK;
}
else
{
    // Get the window handle of the main window of the calling process
    IntPtr windowHandle = Process.GetCurrentProcess().MainWindowHandle;

    if (windowHandle == IntPtr.Zero)
    {
        // No window displayed yet
        DialogResult result = myDialog.ShowDialog();
        return result == DialogResult.OK;
    }
    else
    {
        // Parent window exists on separate thread
        // We want the dialog box to appear in front of the main window in the calling program
        // We would like to be able to do 'myDialog.ShowDialog(windowHandleWrapper)', but that means doing something on the UI thread
        object resultState = null;
        WindowsFormsSynchronizationContext.Current.Send(
            new SendOrPostCallback(delegate(object state) { resultState = myDialog.ShowDialog(); }), resultState);

        if (resultState is DialogResult)
        {
            DialogResult result = (DialogResult) resultState;
            return result == DialogResult.OK;
        }
        else
            return false;

    }
}

}

Answer 3

It would appear that is behaviour is specific to XP... Hence I can't reproduce it on Vista.

http://www.gamedev.net/community/forums/topic.asp?topic_id=218484

EDIT: PS: It's past my bedtime (2 AM;-).

Thanx all for your responses... there's a "few things" I can try... I might even go into the office tomorrow to try them... Yeah, yeah... I had a life once, but I traded it for a haircut and a job ;-)

Cheers all. Keith.

Answer 4

This did the job perfectly :

formxx.WindowState = FormWindowState.Normal;
formxx.BringToFront();
formxx.Topmost=true;
formxx.Focus();

Answer 5

I got a code in the project.

private static extern bool SetForegroundWindow(
IntPtr hWnd); 
public static void ShowToFront(Form form)
{
    FormWindowState oldState = form.WindowState;
    form.WindowState = FormWindowState.Minimized;
    form.Show();

    form.Activate();
    form.TopLevel = false;
    form.TopLevel = true;
    form.SelectNextControl(form.ActiveControl, true, true, true, true);
    SetForegroundWindow(form.Handle);
    form.Focus();
    form.WindowState = oldState;
}