RadGridView - Column DataTrigger change the Content Size - Why?

[Thomas]

<telerik:RadGridView    Grid.Row="1"
                                        AutoGenerateColumns="False"
                                            IsFilteringAllowed="False" CanUserResizeColumns="False" ShowGroupPanel="False"
                                                RowIndicatorVisibility="Collapsed"
                                                    SelectionMode="Single" SelectionUnit="FullRow"
                                                        telerik:StyleManager.Theme="Windows8Touch"
                                                            ItemsSource="{Binding Rückstellproben_RadGridView}"
                                                                SelectedItem="{Binding Rückstellproben_RadGridView_SelectedItem, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">

    <telerik:GridViewDataColumn
                                                    Header="Freigabe"
                                                        HeaderTextAlignment="Center"
                                                            MinWidth="120">

                        <telerik:GridViewDataColumn.CellTemplate>

                            <DataTemplate>

                                <telerik:RadButton  Content="Bestätigen"
                                                        IsEnabled="False"
                                                            Margin="3, 0, 3, 0"/>

                            </DataTemplate>

                        </telerik:GridViewDataColumn.CellTemplate>

                        <telerik:GridViewDataColumn.CellEditTemplate>

                            <DataTemplate>

                                <telerik:RadButton  Content="Bestätigen"
                                                        x:Name="rb_Stellplatzfreigabe_der_dritten_Rückstellprobe"
                                                            Margin="3, 0, 3, 0">

                                    <telerik:RadButton.Style>

                                        <Style TargetType="telerik:RadButton">

 

                                        <Style.Triggers>

                                            <DataTrigger Binding="{Binding Rückstellproben_RadGridView_Kryobox_Position_dritte_Probe_ID}" Value="{x:Null}">

                                                <Setter Property="IsEnabled" Value="True"/>

                                            </DataTrigger>
                                            
                                        </Style.Triggers>

                                        </Style>

                                   </telerik:RadButton.Style/>

                                </telerik:RadButton>

 

                            </DataTemplate>

 

                       </telerik:GridViewDataColumn.CellEditTemplate>

</telerik:GridViewDataColumn/>

</telerik:RadGridView>

(Left Picture - CellTemplate / Right Picture - CellEditTemplate with DataTrigger / Bottom - if i try to change the Height)

Greets