New Post: PropertyGrid

The Xaml designer is throwing the following error:
"Cannot modify TargetProperties once the definition has beed added to a collection."

on this line.

<xctk:EditorTemplateDefinition TargetProperties="EditorFont">

<xctk:PropertyGrid x:Name="testPropertyGrid" Margin="10,10,10,72" ShowSearchBox="False" ShowSortOptions="False">
            <xctk:PropertyGrid.EditorDefinitions>
                <xctk:EditorTemplateDefinition TargetProperties="EditorFont">
                    <xctk:EditorTemplateDefinition.EditingTemplate>
                        <DataTemplate>
                            <StackPanel Orientation="Horizontal">
                                <TextBlock Text="{Binding Value.Family}" />
                                <TextBlock Text=", " />
                                <TextBlock Text="{Binding Value.FontSize}" />
                                <TextBlock Text=", " />
                                <TextBlock Text="{Binding Value.Weight}" />
                                <TextBlock Text=", " />
                                <TextBlock Text="{Binding Value.Style}" />
                                <TextBlock Text=", " />
                                <TextBlock Text="{Binding Value.Stretch}" />
                            </StackPanel>
                        </DataTemplate>
                    </xctk:EditorTemplateDefinition.EditingTemplate>
                </xctk:EditorTemplateDefinition>
            </xctk:PropertyGrid.EditorDefinitions>
        </xctk:PropertyGrid>

Otherwise the propertygrid works fine.

Mark