GridView在顶部有一个缺口

Question

我使用的是GridView，但最重要的是它有一个缺口。我怎么能摆脱它呢？ picture
黑色边框应该代表GridView
感谢

包含GridView的xml部分： `                                                                                                                                                                                                                                    

            <Notification:SfHubTile x:Name="informationTile" Grid.Column="0" FontSize="13" Grid.Row="0"/>
            <Notification:SfHubTile x:Name="testSettingTile" Content="Testsetting = ?" FontSize="13" Grid.Column="4" Grid.Row="0"/>
            <Button x:Name="addTest" Grid.Column="2" HorizontalAlignment="Left" Margin="40,0,0,0" Grid.Row="1" VerticalAlignment="Center" BorderThickness="0" Click="addTest_Click"/>
            <GridView ItemsSource="{Binding}" x:Name="testsGridView" Grid.Column="2"  Margin="0,0,0,0" >
                <GridView.ItemTemplate>
                    <DataTemplate>
                        <Notification:SfHubTile Width="300" Height="200"  Tapped="tile_Tapped" RightTapped="testRightClicked" Holding="testTileHold">
                            <Grid>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="Auto"/>
                                    <ColumnDefinition/>
                                </Grid.ColumnDefinitions>
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="500*"/>
                                </Grid.RowDefinitions>
                                <TextBox Text="{Binding Path=name, Mode=OneTime}" Margin="10,0,0,0" FontSize="15"  TextWrapping="Wrap" Background="Transparent"
                                         BorderThickness="0" Grid.Column="0" Grid.Row="0" LostFocus="name_LostFocus" Name="folder"/>
                                <TextBlock Margin="0,5,0,5" Text="Anzahl Fragebögen im Test: " FontSize="13" Grid.Row="1" Grid.Column="0"/>
                                <TextBlock Margin="20,5,0,5" Text="{Binding Path=numberOfQuestionaires, Mode=TwoWay}" FontSize="13" Grid.Row="1" Grid.Column="1"/>
                                <TextBlock Margin="0,5,0,5" FontSize="13" Text="Anzahl der Propanten: " Grid.Row="2" Grid.Column="0"/>
                                <TextBlock Margin="20,5,0,5" FontSize="13" Text="{Binding Path=numberOfProbands, Mode=TwoWay}" Grid.Row="2" Grid.Column="1"/>
                                <TextBlock FontSize="13" Text="Beschreibung: " Grid.Row="3" Grid.Column="0"/>
                                <ScrollViewer HorizontalScrollMode="Disabled" HorizontalScrollBarVisibility="Disabled" VerticalScrollBarVisibility="Auto" Grid.Row="3" Grid.Column="1" Margin="0,5,0,5">
                                    <TextBox Margin="20,0,0,0" FontSize="13" BorderThickness="0" Text="{Binding Path=description, Mode=TwoWay}" Background="Transparent"
                                             TextWrapping="Wrap" Grid.Row="3" Grid.Column="1"/>
                                </ScrollViewer>
                            </Grid>
                        </Notification:SfHubTile>
                    </DataTemplate>
                </GridView.ItemTemplate>
            </GridView>
        </Grid>
    </ScrollViewer>

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