Question

In my WPF app, I sometimes being up a System.Windows.MessageBox. When it is initially displayed, it is shown on top of my main application window, as I would like. Is there a way that I can force it to ALWAYS remain top of the main window? The problem I have is that when a MessageBox is displayed, users can then click on the main app window and bring it to the front, meaning the MessageBox becomes hidden from view. In this case the user might not realize it’s there, or forget about it, and to them, the main app seems to have frozen.

I’ve read a number of threads about this, but none have resolved the problem for me.

I ought to add that the thread putting up the MessageBox might not be the UI thread.
Thanks
Tom

Answer 1

Use the version of MessageBox.Show that takes a Window “owner” and pass your window.

MessageBox.Show(Application.Current.MainWindow, "Im always on top - of the main window");

If your possibly not on the UI thread try:

string msg="Hello!";
if (Application.Current.Dispatcher.CheckAccess()) {
    MessageBox.Show(Application.Current.MainWindow, msg);
}
else {
    Application.Current.Dispatcher.Invoke(DispatcherPriority.Normal, new Action(()=>{
        MessageBox.Show(Application.Current.MainWindow, msg);
    }));
}

You can:
1. Invoke to block your thread until MessageBox is dismissed OR
2. BeginInvoke in which case your thread code will continue to execute but UI thread will block on MessageBox until its dismissed).