To stop scrolling, limiting the size of the contained content to its own size, make sure you set
ScrollView Orientation = "Horizontal" or "Both" or "Vertical" respectively.
i.e. for your example -
<ScrollView Orientation="Horizontal" Grid.Row="1" Grid.Column="0" Grid.ColumnSpan="3" HorizontalOptions="FillAndExpand" x:Name="attachmentScroller"> <StackLayout WidthRequest="1000" x:Name="AttachmentsView" Orientation="Horizontal" VerticalOptions="Fill"/> </ScrollView>
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