Synchronize scroll position between two controls - Scroll Position not updating

[voidray]

I try to sync the scroll position of two AvaloniaEdit controls that are places beside eachother in a grid.
The line to scroll to is actually determined correctly. I did very that by writing currentLineSource to the console.
This is the code behind of the View (Constructor calls SetupEditors()):

private void SetupEditors()
{
   leftEditor.TextArea.TextView.ScrollOffsetChanged += (s, e) => SyncScroll(leftEditor, rightEditor);
   rightEditor.TextArea.TextView.ScrollOffsetChanged += (s, e) => SyncScroll(rightEditor, leftEditor);
}

private void SyncScroll(TextEditor source, TextEditor target)
{
   var currentLineSource = GetLineNumberFromVerticalOffset(source, source.VerticalOffset);
   target.ScrollToLine(currentLineSource);
}

public int GetLineNumberFromVerticalOffset(TextEditor editor, double verticalOffset)
{
	var textView = editor.TextArea.TextView;
	int estimatedLineNumber = Math.Max(1, (int)(verticalOffset / textView.DefaultLineHeight) + 1);
	estimatedLineNumber = Math.Min(estimatedLineNumber, editor.Document.LineCount);
}

[danipen]

I recommend you to synchronize using the scroll offset

[voidray]

With ScrollToVerticalOffset also nothing happens:

var offset = (currentLineSource - 1) * target.TextArea.TextView.DefaultLineHeight;
target.ScrollToVerticalOffset(offset);

This is the View I'm using:

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             xmlns:vm="using:TestProject.Av.ViewModels"
             xmlns:avedit="clr-namespace:AvaloniaEdit;assembly=AvaloniaEdit"
             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
             x:Class="TestProject.Av.Views.TextView">
   <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <TextBlock Text="test" Grid.Row="0" />
        <Grid Grid.Row="1">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>

            <avedit:TextEditor x:Name="leftEditor" Grid.Column="0" FontSize="14" ShowLineNumbers="True">
            </avedit:TextEditor>

            <avedit:TextEditor x:Name="rightEditor" Grid.Column="1" FontSize="14" ShowLineNumbers="True">
            </avedit:TextEditor>
        </Grid>
    </Grid>
    
</UserControl>

[voidray]

I did some more testing by creating a blank project with just two AvaloniaEdit controls and a button.
When I use the button to call ScrollToVerticalOffset then nothing happens.
ScrollToLine works. The issue with the code I posted above was that the expected line position is not at the top but in the center (vertically).
(The code also the issue that when setting the position of the other control, the event gets fired again and tries to update the control where the user scrolled. It's not relevant to the topic here however. The issue with ScrollToVerticalOffset can be reproduced with a simple Button)