Bring a window to the front in WPF

Question

How can I bring my WPF application to the front of the desktop? So far I've tried:

SwitchToThisWindow(new WindowInteropHelper(Application.Current.MainWindow).Handle, true);

SetWindowPos(new WindowInteropHelper(Application.Current.MainWindow).Handle, IntPtr.Zero, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE);

SetForegroundWindow(new WindowInteropHelper(Application.Current.MainWindow).Handle);

None of which are doing the job (Marshal.GetLastWin32Error() is saying these operations completed successfully, and the P/Invoke attributes for each definition do have SetLastError=true).

If I create a new blank WPF application, and call SwitchToThisWindow with a timer, it works exactly as expected, so I'm not sure why it's not working in my original case.

Edit: I'm doing this in conjunction with a global hotkey.

Answer 1

Well I figured out a work around. I'm making the call from a keyboard hook used to implement a hotkey. The call works as expected if I put it into a BackgroundWorker with a pause. It's a kludge, but I have no idea why it wasn't working originally.

void hotkey_execute()
{
    IntPtr handle = new WindowInteropHelper(Application.Current.MainWindow).Handle;
    BackgroundWorker bg = new BackgroundWorker();
    bg.DoWork += new DoWorkEventHandler(delegate
        {
            Thread.Sleep(10);
            SwitchToThisWindow(handle, true);
        });
    bg.RunWorkerAsync();
}

Answer 2

myWindow.Activate();

Attempts to bring the window to the foreground and activates it.

That should do the trick, unless I misunderstood and you want Always on Top behavior. In that case you want:

myWindow.TopMost = true;

Answer 3

If the user is interacting with another application, it may not be possible to bring yours to the front. As a general rule, a process can only expect to set the foreground window if that process is already the foreground process. (Microsoft documents the restrictions in the SetForegroundWindow() MSDN entry.) This is because:

1. The user "owns" the foreground. For example, it would be extremely annoying if another program stole the foreground while the user is typing, at the very least interrupting her workflow, and possibly causing unintended consequences as her keystrokes meant for one application are misinterpreted by the offender until she notices the change.
2. Imagine that each of two programs checks to see if its window is the foreground and attempts to set it to the foreground if it is not. As soon as the second program is running, the computer is rendered useless as the foreground bounces between the two at every task switch.

Answer 4

The problem could be that the thread calling your code from the hook hasn't been initialized by the runtime so calling runtime methods don't work.

Perhaps you could try doing an Invoke to marshal your code on to the UI thread to call your code that brings the window to the foreground.

Answer 5

In case you need the window to be in front the first time it loads then you should use the following:

private void Window_ContentRendered(object sender, EventArgs e) { this.Topmost = false; }

private void Window_Initialized(object sender, EventArgs e) { this.Topmost = true; }

Answer 6

I have had a similar problem with a WPF application that gets invoked from an Access application via the Shell object.

My solution is below - works in XP and Win7 x64 with app compiled to x86 target.

I'd much rather do this than simulate an alt-tab.

void Window_Loaded(object sender, RoutedEventArgs e)
{
    // make sure the window is normal or maximised
    // this was the core of the problem for me;
    // even though the default was "Normal", starting it via shell minimised it
    this.WindowState = WindowState.Normal;

    // only required for some scenarios
    this.Activate();
}