"Ensure Event Failed" error occur

Question

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:CustomCalc">
    <Style TargetType="{x:Type local:CustomControl1}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:CustomControl1}">

                    <TextBlock Text="welcome" Height="50" Width="150" MouseDown=""/>

                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

In the above program, (in the program i workout in custom control library) I am trying to change the control textblock => button.(textblock act as button functionality) so i try to add a event to the textblock it gives a error message "ensure event failed", And this file name is "Generic.xaml" so i add a class "Generic.xaml.cs" but same error is show on. Please explain why it should occur and how to resolve it, thanks in advance.

Answer 1

You need to add a x:Class attribute to support event handlers in the XAML file. So your Generic.xaml should look like this:

<ResourceDictionary
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:CustomCalc"
    x:Class="CustomCalc.Generic">
    <Style TargetType="{x:Type local:CustomControl1}">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type local:CustomControl1}">
                    <TextBlock Text="welcome" Height="50" Width="150" MouseDown="TextBlock_MouseDown"/>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>

And as for the Generic.xaml.cs :

namespace CustomCalc
{
    public partial class Generic : ResourceDictionary
    {
        private void TextBlock_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {

        }
    }
}

Also don't forget to merge your ResourceDictionary in the App.Xaml file:

<Application.Resources>
    <ResourceDictionary >
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="pack://application:,,,/CustomCalc;component/Generic.xaml" />
        </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
</Application.Resources>