MARKUS

<UserControl x:Name="userControl" x:Class="KCOM.Controls.ExtendTextBox"

             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 

             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 

             xmlns:local="clr-namespace:KCOM.Controls"

             xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"

             mc:Ignorable="d" 

             d:DesignHeight="450" d:DesignWidth="120">

    <UserControl.Resources>

        <telerik:InvertedBooleanToVisibilityConverter x:Key="InvertedBooleanToVisibility"/>

        <telerik:BooleanToVisibilityConverter x:Key="BooleanToVisibility"/>

    </UserControl.Resources>

    <Grid>

        <Grid.ColumnDefinitions>

            <ColumnDefinition Width="Auto"/>

            <ColumnDefinition Width="Auto"/>

        </Grid.ColumnDefinitions>

        <TextBlock x:Name="txtBox"

                       Text="{Binding Text, ElementName=userControl}" TextWrapping="WrapWithOverflow"  Margin="5,3,3,3"/>

        <Button Grid.Column="1" x:Name="btExtend" Height="20" Content="+" VerticalAlignment="Top" Click="Button_Click"/>

        <!--<Expander IsExpanded="False">

            <Expander.Template>

                <ControlTemplate TargetType="{x:Type Expander}">

                    <Border>

                        <Grid>

                            <Grid.RowDefinitions>

                                <RowDefinition Height="Auto"/>

                                <RowDefinition/>

                            </Grid.RowDefinitions>

                            <ContentPresenter x:Name="ExpandSite" Grid.RowSpan="2"/>

                            <ToggleButton x:Name="HeaderSite"

                                  ContentTemplate="{TemplateBinding HeaderTemplate}"

                                  Content="{TemplateBinding Header}" HorizontalAlignment="Left"

                                  IsChecked="{Binding IsExpanded, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Background="{x:Null}" BorderBrush="{x:Null}" />

                        </Grid>

                    </Border>

                </ControlTemplate>

            </Expander.Template>

            <Expander.Header>

                <TextBlock Visibility="{Binding IsExpanded, RelativeSource={RelativeSource AncestorType={x:Type Expander}, Mode=FindAncestor}, 

                 Converter={StaticResource InvertedBooleanToVisibility}}" Height="24"

                           TextTrimming="WordEllipsis"  FlowDirection="LeftToRight" TextWrapping="NoWrap"

                           Text="{Binding Text, ElementName=userControl}"/>

            </Expander.Header>

            <TextBlock x:Name="txtBox" Visibility="{Binding IsExpanded, RelativeSource={RelativeSource AncestorType={x:Type Expander}, Mode=FindAncestor}, 

                 Converter={StaticResource BooleanToVisibility}}"

                       Text="{Binding Text, ElementName=userControl}" TextWrapping="Wrap" Margin="5,3,3,3" FlowDirection="LeftToRight"/>

        </Expander>-->

    </Grid>

</UserControl>