Wpf - bestway to register a change on property - wpf

Question

Whatsup, I'm new to wpf technology and im having trouble to find out how to popup a message on screen when there is a change on the User property. (Except that, the code works perfect).
*My goal is to register an exsisting event that takes care of it and NOT to do it in the MyData class by rewriting the 'Set'.
xaml:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1"
Title="MainWindow" Height="350" Width="525">
<StackPanel x:Name="MyGrid1">
<StackPanel.Resources>
<local:MyData x:Key="mySource1"
User="Arik2" />
</StackPanel.Resources>
<TextBox x:Name="target1"
Grid.Row="1"
Grid.Column="2"
Text="{Binding Source={StaticResource mySource1}, Path=User,Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
<TextBox x:Name="target2"
Grid.Row="2"
Grid.Column="2"
Text="{Binding Source={StaticResource mySource1}, Path=User,Mode=OneWay, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
</Window>
Thats my app code:
namespace WpfApplication1
{
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}
}
public class MyData
{
public string User { get; set; }
}
}
Thank you all.

Answer 1

For the textboxes you have you can always open a message window in a textchanged event handler.
For example
<TextBox TextChanged="txt_TextChanged" >
Private Sub txt_TextChanged(sender As System.Object, e As System.Windows.Controls.TextChangedEventArgs)
MessageBox.Show("Value changed")
End Sub
Note this is probably what you are looking for but is triggering off the text in the box changing not the property itself. If you use anything like validation and input invalid data this event will fire but the text will not change.
I think you can use the sourcechanged event to get exactly what you want.