To support touch operations, we can't disable `HorizontalScrollMode` and `VerticalScrollMode`. The following seems to work. Can you give it a try?
```xaml <Grid ColumnDefinitions="*,Auto"> <Grid Grid.Column="0" ColumnDefinitions="*,*" PointerWheelChanged="Grid_PointerWheelChanged" SizeChanged="Grid_SizeChanged"> <Grid.Resources> <Style BasedOn="{StaticResource DefaultScrollViewerStyle}" TargetType="ScrollViewer"> <Setter Property="VerticalAlignment" Value="Top" /> <Setter Property="HorizontalScrollBarVisibility" Value="Hidden" /> <Setter Property="VerticalScrollBarVisibility" Value="Hidden" /> <!-- <Setter Property="HorizontalScrollMode" Value="Disabled" /> <Setter Property="VerticalScrollMode" Value="Disabled" /> --> </Style> </Grid.Resources> <ScrollViewer x:Name="LeftScrollViewer" Grid.Column="0" ViewChanged="LeftScrollViewer_ViewChanged"> <TextBlock FontSize="2048" Text="Left" /> </ScrollViewer> <ScrollViewer x:Name="RightScrollViewer" Grid.Column="1" ViewChanged="RightScrollViewer_ViewChanged"> <TextBlock FontSize="1024" Text="Right" /> </ScrollViewer> </Grid> <ScrollBar x:Name="VerticalScrollBar" Grid.Column="1" IndicatorMode="MouseIndicator" ValueChanged="VerticalScrollBar_ValueChanged" /> </Grid> ```
```cs private void Grid_SizeChanged(object sender, SizeChangedEventArgs e) { VerticalScrollBar.ViewportSize = e.NewSize.Height; VerticalScrollBar.Maximum = Math.Max(LeftScrollViewer.ScrollableHeight, RightScrollViewer.ScrollableHeight); }
private void Grid_PointerWheelChanged(object sender, PointerRoutedEventArgs e) { VerticalScrollBar.Value = Math.Max(0, Math.Min(this.VerticalScrollBar.Maximum, this.VerticalScrollBar.Value - e.GetCurrentPoint(this).Properties.MouseWheelDelta)); }
private void VerticalScrollBar_ValueChanged(object sender, RangeBaseValueChangedEventArgs e) { if (e.NewValue < 0 || e.NewValue > this.VerticalScrollBar.Maximum) return;
this.LeftScrollViewer.ScrollToVerticalOffset(e.NewValue); this.RightScrollViewer.ScrollToVerticalOffset(e.NewValue); }
private void LeftScrollViewer_ViewChanged(object sender, ScrollViewerViewChangedEventArgs e) { if (sender is not ScrollViewer scrollViewer) return;
VerticalScrollBar.Value = scrollViewer.VerticalOffset; }
private void RightScrollViewer_ViewChanged(object sender, ScrollViewerViewChangedEventArgs e) { if (sender is not ScrollViewer scrollViewer) return;
VerticalScrollBar.Value = scrollViewer.VerticalOffset; } ```

I tried your approach using [RenderTransform](https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.uielement.rendertransform?view=windows-app-sdk-1.7&WT.mc_id=%3Fwt.mc_id%3DMVP_356303) with [TranslateTransform](https://learn.microsoft.com/en-us/windows/windows-app-sdk/api/winrt/microsoft.ui.xaml.media.translatetransform?view=windows-app-sdk-1.7&WT.mc_id=%3Fwt.mc_id%3DMVP_356303), but the UI ended up feeling a bit rough. This is what worked better for me:
```xaml <Grid ColumnDefinitions="*,Auto"> <Grid Grid.Column="0" ColumnDefinitions="*,*" PointerWheelChanged="Grid_PointerWheelChanged" SizeChanged="Grid_SizeChanged"> <Grid.Resources> <Style BasedOn="{StaticResource DefaultScrollViewerStyle}" TargetType="ScrollViewer"> <Setter Property="VerticalAlignment" Value="Top" /> <Setter Property="HorizontalScrollBarVisibility" Value="Hidden" /> <Setter Property="VerticalScrollBarVisibility" Value="Hidden" /> <Setter Property="HorizontalScrollMode" Value="Disabled" /> <Setter Property="VerticalScrollMode" Value="Disabled" /> </Style> </Grid.Resources> <ScrollViewer x:Name="LeftScrollViewer" Grid.Column="0"> <TextBlock FontSize="2048" Text="Left" /> </ScrollViewer> <ScrollViewer x:Name="RightScrollViewer" Grid.Column="1"> <TextBlock FontSize="1024" Text="Right" /> </ScrollViewer> </Grid> <ScrollBar x:Name="VerticalScrollBar" Grid.Column="1" IndicatorMode="MouseIndicator" ValueChanged="VerticalScrollBar_ValueChanged" /> </Grid> ```
```cs private void Grid_SizeChanged(object sender, SizeChangedEventArgs e) { VerticalScrollBar.ViewportSize = e.NewSize.Height; VerticalScrollBar.Maximum = Math.Max(LeftScrollViewer.ScrollableHeight, RightScrollViewer.ScrollableHeight); }
private void Grid_PointerWheelChanged(object sender, PointerRoutedEventArgs e) { VerticalScrollBar.Value = Math.Max(0, Math.Min(this.VerticalScrollBar.Maximum, this.VerticalScrollBar.Value - e.GetCurrentPoint(this).Properties.MouseWheelDelta)); }
private void VerticalScrollBar_ValueChanged(object sender, RangeBaseValueChangedEventArgs e) { if (e.NewValue < 0 || e.NewValue > this.VerticalScrollBar.Maximum) return;
this.LeftScrollViewer.ScrollToVerticalOffset(e.NewValue); this.RightScrollViewer.ScrollToVerticalOffset(e.NewValue); } ```