使用了UniformGrid 后不能滚动了，求大佬指点迷津

  <ItemsControl ItemsSource="{Binding Apps}">
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <UniformGrid Columns="3" Rows="2"/>
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <Button Style="{DynamicResource ApplicationItemStyle}">
                            <Button.ContextMenu>
                                <ContextMenu>
                                    <MenuItem Header="修改"/>
                                    <MenuItem Header="删除"/>
                                </ContextMenu>
                            </Button.ContextMenu>
                        </Button>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
                <ItemsControl.Template>
                    <ControlTemplate>
                        <hc:ScrollViewer x:Name="ScrollViewer">
                            <ItemsPresenter/>
                        </hc:ScrollViewer>
                    </ControlTemplate>
                </ItemsControl.Template>
            </ItemsControl>