Silverlight 4 Overloaded Textbox's textchanged event is fired by parent textbox - silverlight-4.0

Question

I have an custom textbox that I got from http://blog.roboblob.com/2010/07/16/custom-silverlight-textbox-control-that-immediately-updates-databound-text-property-in-twoway-binding/comment-page-1/:
public class ImmediateTextBox : TextBox
{
public ImmediateTextBox()
{
this.Loaded += ImmediateTextBox_Loaded;
}
void ImmediateTextBox_Loaded(object sender, RoutedEventArgs e)
{
this.GotFocus += ImmediateTextBox_GotFocus;
this.TextChanged += new TextChangedEventHandler(ImmediateTextBox_TextChanged);
}
void ImmediateTextBox_TextChanged(object sender, TextChangedEventArgs e)
{
TextBox txt = sender as TextBox;
if (txt != null)
{
BindingExpression bindExp = txt.GetBindingExpression(TextBox.TextProperty);
if (bindExp != null)
{
bindExp.UpdateSource();
}//if
}//if
}
void ImmediateTextBox_GotFocus(object sender, RoutedEventArgs e)
{
this.SelectAll();
}
}
In my xaml I am using this, and it works fine, except when I have it nested and the parent container has a ImmediateTextBox:
<ItemsControl Grid.Column="1" ItemsSource="{Binding Path=LstForecast}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<customControls:ImmediateTextBox Padding="8" Height="36" Text="{Binding Path=DForecastQuantityShippedTotal,
StringFormat=\{0:n0\},
Mode=TwoWay,
Converter={StaticResource StringToNullableDoubleConverter}}"
Width="70" IsEnabled="{Binding Path=IsForecastUserEditable}"/>
<!--Weeks-->
<ItemsControl ItemsSource="{Binding Path=LstWeeks}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<customControls:ImmediateTextBox Padding="8" Width="70" Height="36"
Text="{Binding Path=DForecastQuantityShippedTotal, StringFormat=\{0:n0\}, Mode=TwoWay, Converter={StaticResource StringToNullableDoubleConverter}}"
IsEnabled="{Binding Path=IsForecastUserEditable}"/>
<!--days data-->
<ItemsControl ItemsSource="{Binding Path=LstDays}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<customControls:ImmediateTextBox Padding="8" Width="70" Height="36"
Text="{Binding Path=DForecastAutoManual,
StringFormat=\{0:n0\},
Mode=TwoWay,
Converter={StaticResource StringToNullableDoubleConverter}}"
IsEnabled="{Binding Path=IsForecastUserEditable}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
<!--end days data-->
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
<!--end weeks-->
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
At the lowest level it gets really funky. modifying the previous and sometimes the following generated textboxes. If I use an autocompletebox, of course it works. The problem is that I am wanting to add behaviors to the textbox for copy/paste/selectall, etc that I can't do with the autocompletebox, since there is no selectedtext or a selectall() method. Also I noticed in the RoutedEventArgs, the originalsource is null. I figured using that would cause it to work, but no. Any help? thanks in advance.

Answer 1

Okay so I figured it out. I have each text-box bound to properties. When any one of these text-boxes are modified then the bound properties of the ViewModel update each other. When that happens they update the text-box where it occurs and not just the property, because it is a 2-way binding. So when there is an update that is caused by the user's input it updates. It shouldn't when the user doesn't type anything in that text-box (when the text-box is being updated from the algorithm.
My solution is creating a boolean property "isUser" in ImmediateTextBox. When my overridden OnKeyDown or OnMouseLeftButtonPressed are called I set isUser to true. When the text changes from the user typing in or pasting in something, then i update the binding and set isUser to false.