get text from textbox inside listview

Hi ,

i have this listview in wpf , which has a gridviewcolumn that has textbox, now i am stuck how to get the text inside the textboxes for that particular datarowview or say for the selected item of the listliew.  

Following is the xaml , a code to get the textbox value in vb.net will be appreciated. thanks in advance

Grid >
        <Grid.Resources>
            <Style TargetType="ListViewItem">
                <Setter Property="HorizontalContentAlignment" Value="Stretch" />
                <Setter Property="VerticalContentAlignment" Value="Stretch" />
            </Style>
        </Grid.Resources>

        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*"></ColumnDefinition>
            <ColumnDefinition Width="75"></ColumnDefinition>
        </Grid.ColumnDefinitions>

        <ListView Grid.Column="0" x:Name="lstViewConditionItems"                     
                     ItemsSource="{Binding ElementName=aletConditionItems, Path=DataContext.Items}"                          
                     SelectedItem="{Binding ElementName=aletConditionItems, Path=DataContext.SelectedItem, Mode=TwoWay}">
            <ListView.View>
                <GridView>
                    <GridViewColumn Header="Column Id" >
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <ComboBox SelectedValue="{Binding Path=ColumnId}" Margin="-6,-2,-6,-2"                
                    ItemsSource="{Binding ElementName=aletConditionItems, Path=DataContext.ColumnIds}" />
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>

                    <GridViewColumn Header="Value" Width="100" >
                        <GridViewColumn.CellTemplate>
                            <DataTemplate>
                                <TextBox Text="Only backSpace and SpaceBar works" ></TextBox>
                            </DataTemplate>
                        </GridViewColumn.CellTemplate>
                    </GridViewColumn>

<GridViewColumn Header="test" Width="100" >
                     
                            
                    </GridViewColumn>

                </GridView>
            </ListView.View>
        </ListView>

        <StackPanel Orientation="Horizontal" Grid.Column="1" VerticalAlignment="Top" >
            <Button Content="+" Width="30" Command="{Binding ElementName=aletConditionItems, Path=DataContext.OnAddConditionItem}" Name="Button1"></Button>
        </StackPanel>
    </Grid>