Hi Mikhail,
Thanks for your code and I can reproduce the issue that you are facing. A strange dark green line appears while ZoomFactor is not 1, not only 0.9, but also when the value is 1.1, the same thing happens.
However I don't think the issue locates on ScrollViewer, it might be a
ScaleTransform issue, if we have following code, scale the gird without the help of ScrollViewer, we shall see the dark green line either(the fourth Gird sample in your project). ScrollViewer is only applying the ScaleTransform for Gird inside it.
<StackPanel Grid.Column="1" Grid.Row="1">
<Grid Width="255" Height="255">
<Grid.RenderTransform>
<ScaleTransform ScaleX="1.1" ScaleY="1.1"/>
</Grid.RenderTransform>
<Border Background="Cyan"/>
<Border Background="Black"/>
</Grid>
<TextBlock Text="ScaleTransform.Scale == 0.9"/>
</StackPanel>
Currently I don't have any solution for how to remove the dark line offhand. But I will try to report this issue as a bug to some senior engineers, thank you for submit this.
--James
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Thanks
MSDN Community Support
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