Wpf - Default Button not Working as Expected

Question

I'm having a problem with the default button in the xaml code below -

<Window x:Class="WebSiteMon.Results.Views.GraphicSizeSelectPopUp"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:commonWPF="http://rubenhak.com/common/wpf"
xmlns:WPF="clr-namespace:Bennedik.Validation.Integration.WPF;assembly=Bennedik.Validation.Integration.WPF" 
    ResizeMode="NoResize" WindowStyle="ThreeDBorderWindow" SizeToContent="WidthAndHeight">
<Window.Resources>
    <Style TargetType="{x:Type TextBox}">
        <Setter Property="Validation.ErrorTemplate">
            <Setter.Value>
                <ControlTemplate>
                    <Border BorderBrush="Red" BorderThickness="2" >
                        <AdornedElementPlaceholder />
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Style.Triggers>
            <Trigger Property="Validation.HasError" Value="true">
                <Setter Property="ToolTip"
        Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}"/>
            </Trigger>
        </Style.Triggers>
    </Style>
    </Window.Resources>
<WPF:ErrorProvider x:Name="UrlDataErrorProvider" RulesetName="RuleSetA" >
    <Grid Background="{DynamicResource WindowBackgroundBrush}">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="25" />
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
            <RowDefinition Height="*" />
        </Grid.RowDefinitions>

        <RadioButton Grid.ColumnSpan="2" Margin="10" Name="radioButton1" Content="640 x 480 pixels" 
                 Command="{Binding SelectSizeRb}"  CommandParameter="640,480"/>
        <RadioButton Grid.ColumnSpan="2" Margin="10" Name="radioButton2" Content="800 x 600 pixels" 
                 Command="{Binding SelectSizeRb}"  CommandParameter="800,600" Grid.Row="1" IsChecked="True" />
        <RadioButton Grid.ColumnSpan="2" Margin="10" Name="radioButton3" Content="1024 x 768 pixels" 
                 Command="{Binding SelectSizeRb}"  CommandParameter="1024,768" Grid.Row="2" />
        <RadioButton Grid.ColumnSpan="2" Margin="10" Name="radioButton4"  
                 Command="{Binding SelectSizeRb}"  CommandParameter="0,0" Grid.Row="3" />

        <Button Grid.Column="1" Grid.ColumnSpan="1" Grid.Row="5" Margin="5" Name="BtnOk" IsDefault="True">Ok</Button>
        <Button Grid.Column="2" Grid.ColumnSpan="1" Grid.Row="5" Margin="5" Name="BtnCancel" IsCancel="True">Cancel</Button>

    </Grid>
</WPF:ErrorProvider>

I call the above window using the following code -

       var p = new GraphicSizeSelectPopUp();
        var result = p.ShowDialog() ?? false;
        p.Close();

I'm using this as a Popup window in my application to get some info from the user. My problem is the when I click on the OK button, nothing happens. The Cancel button works exactly as expected, meaning that control returns in the calling program from the ShowDialog method.

As I understand WPF (still newbie), all I have to do is set the IsDefault property to true for the default button to do the same. However, this is not what I'm seeing. When I set a breakpoint on the line after the ShowDialog method, it is not hit when I press the okay button. Only when I press the Cancel button or close the window.

Suggestions for the uninformed?

Answer 1

The IsDefault property only means that this button is "clicked" when the ENTER key is pressed. It doesn't close the dialog, and doesn't set the DialogResult, you have to do it manually in code-behind :

private void BtnOK_Click(object sender, RoutedEventArgs e)
{
    this.DialogResult = true;
    this.Close();
}