MessageBox doesn't take focus

Question

When I click enter-button, MessageBox is shown. I want MessageBox to close when I click enter-button again as usual. Problem is - it doesn't have focus, but TextBox has and when I click enter-button _textBox_OnKeyUp eventhandler is invoked again and again. How can I solve my problem?

Markup:

<Grid>
    <TextBox Name="_textBox"
        Width="100"
        Height="30"
        Background="OrangeRed"
        KeyUp="_textBox_OnKeyUp"/>
</Grid>

Code:

private void _textBox_OnKeyUp(object sender, KeyEventArgs e)
{
    if (e.Key != Key.Enter)
        return;

    MessageBox.Show("Bla-bla");
}

Answer 1

You could use KeyDown event instead because the MessageBox responds to the KeyDown event:

<TextBox Name="_textBox"
         Width="100"
         Height="30"
         Background="OrangeRed"
         KeyDown="_textBox_OnKeyDown"/>

And:

private void _textBox_OnKeyDown(object sender, KeyEventArgs e)
{
    if (e.Key != Key.Enter)
       return;

    MessageBox.Show("Bla-bla");
}