How do I “Hide()” a Modal WPF Window without it closing?

Question

I have a WPF window that is run on a background thread as a sort of "notifier window"... when an event is raised, it displays a message... a user clicks the "Snooze" button and I call this.Visibility = Visibility.Collapsed

The very moment that I hide the window (either by calling this.Hide() or setting the Visibility as mentioned above)... the "ShowDialog()" code releases the window and closes it.

This is absolutely a bug in the WPF code (which I've identified via reflector)... but my question remains. Has anyone been able to come up with a work-around for this issue?

I've tried many things and am now reaching out to ya'll smart people :)

Answer 1

You can't hide a modal dialog. That's like asking, "How do I get to 100mph in reverse?" You don't, you drive the car forwards.

Use Show, not ShowDialog. Alternately you can simply re-ShowDialog when it needs to become visible again.

Answer 2

1. In order to show modal window always use ShowDialog() .

2. Use Close() instead of Hide() .

3. Handle the FormClosing event like that:

private void OnFormClosing(object sender, FormClosingEventArgs e)
    {
        e.Cancel = true;
        this.Visible = false;
    }

Answer 3

Timothy's Answer is good. I just needed for my scenerio to add the following

window.Closed += new EventHandler(window_Closed);
window.Show();
System.Windows.Threading.Dispatcher.Run(); 

and then in the event...

void window_Closed(object sender, EventArgs e)
{
    System.Windows.Threading.Dispatcher.ExitAllFrames();
}

I needed to do this because it was hanging on the Run after the form was really closed.

Answer 4

OK, and as quickly as that - my boss (old C++ goofy guy that he is) figured out the answer.

Here was the code inside of my background thread (which is set to STA mode):

// Show dialog - keeps the thread open and shows the window! Yay!!!
new BeamUI.Notifier.NotifierWindow().ShowDialog();

And here is the modification, that strangely enough works perfectly :)

// Show... hmm, that shows the window... but how do I keep this thread open?
new BeamUI.Notifier.NotifierWindow().Show();

// ZOMG - a line of code that JUST keeps the thread (and msgpump) going!!!
System.Windows.Threading.Dispatcher.Run();

And that's it.

This kinda thing makes me hate C++ people though, and makes me want to just say "if you just built it right in the first place I wouldn't have to look for a work-around!" (j/k)