Datagrid using usercontrol

Question

Hello

I am fighting with this problem: I have a usercontrol which contains a textbox and a button (the button calls some functions to set the textbox's text), here is the xaml:

<UserControl x:Class="UcSelect"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Name="Control1Name"

<Grid x:Name="grid1" MaxHeight="25">
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition Width="25"/>
    </Grid.ColumnDefinitions>
    <Grid.RowDefinitions>
        <RowDefinition Height="25"/>
    </Grid.RowDefinitions>
    <TextBox x:Name="txSelect" Text="{Binding UcText, Mode=TwoWay}" />
    <Button x:Name="pbSelect" Background="Red" Grid.Column="1" Click="pbSelect_Click">...</Button>
</Grid>

And here the code behind:

Partial Public Class UcSelect

Private Shared Sub textChangedCallBack(ByVal [property] As DependencyObject, ByVal args As DependencyPropertyChangedEventArgs)
    Dim UcSelectBox As UcSelect = DirectCast([property], UcSelect)
End Sub

Public Property UcText() As String
    Get
        Return GetValue(UcTextProperty)
    End Get

    Set(ByVal value As String)
        SetValue(UcTextProperty, value)
    End Set
End Property

Public Shared ReadOnly UcTextProperty As DependencyProperty = _
                       DependencyProperty.Register("UcText", _
                       GetType(String), GetType(UcSelect), _
                       New FrameworkPropertyMetadata(String.Empty, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, New PropertyChangedCallback(AddressOf textChangedCallBack)))

Public Sub New()

    InitializeComponent()
    grid1.DataContext = Me

End Sub

Private Sub pbSelect_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs)

    'just demo 
    UcText = UcText + "!"

End Sub

End Class

The UserControl works fine when used as a single control in this way:

    <local:UcSelect Grid.Row="1" x:Name="ucSingle1" UcText="{Binding FirstName, Mode=TwoWay}"/>

Now I wanted to use the control in a custom datagrid column. As I like to have binding support I choosed to derive from DataGridtextColumn instead of using a DataGridTemplateColumn, here is the derived column class:

Public Class DerivedColumn Inherits DataGridTextColumn

Protected Overloads Overrides Function GenerateElement(ByVal oCell As DataGridCell, ByVal oDataItem As Object) As FrameworkElement

    Dim oElement = MyBase.GenerateElement(oCell, oDataItem)
    Return oElement

End Function

Protected Overloads Overrides Function GenerateEditingElement(ByVal oCell As DataGridCell, ByVal oDataItem As Object) As FrameworkElement

    Dim oUc As New UcSelect
    Dim oBinding As Binding = CType(Me.Binding, Binding)
    oUc.SetBinding(UcSelect.UcTextProperty, oBinding)
    Return oUc

End Function

End Class

The column is used in xaml in the following way:

            <local:DerivedColumn Header="Usercontrol" Binding="{Binding FirstName, Mode=TwoWay}"></local:DerivedColumn>

If I start my program all seems to be fine, but changes I make in the custom column are not reflected in the object (property "FirstName"), the changes are simply rolled back when leaving the cell. I think there must be something wrong with my GenerateEditingElement code, but have no idea ... Any Help would really be appreciated

Regards Klaus