Bindings to Text property in TextBox doesnt work

I don’t know why binding to Text doesnt work in TextBox https://github.com/pelmenstar1/test-projects/blob/master/AvaloniaBindingTest/ViewModels/MainWindowViewModel.cs

public class MainWindowViewModel : ViewModelBase
    {
        private string _str = "#0000";
        public string String
        {
            get => _str;
            set
            {
                if (value!= null && value.Length > 0 && value[0] == '#' && value.Length <= 5)
                {
                    _str = value;
                }

                this.RaisePropertyChanged(nameof(String));
            }
        }
    }

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="clr-namespace:AvaloniaBindingTest.ViewModels;assembly=AvaloniaBindingTest"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="AvaloniaBindingTest.Views.MainWindow"
        Icon="/Assets/avalonia-logo.ico"
        Title="AvaloniaBindingTest">

    <Design.DataContext>
        <vm:MainWindowViewModel/>
    </Design.DataContext>

    <TextBox Text="{Binding String, Mode=TwoWay}" HorizontalAlignment="Center" VerticalAlignment="Center"/>

</Window>

[grokys]

Hmm, that line was added by https://github.com/AvaloniaUI/Avalonia/commit/a222fa9b0c2c14380db40d98dd553f2d744517f2:

Don’t modify text due to binding when typing.

If a TextBox is e.g. bound to an int and the user types “02” then the TextBox text should be “02” - not the value that comes back from the binding which will be “2”.

This was added in #691 back in 2016. However cross-checking with WPF, WPF doesn’t seem to have this behavior. If a TextBox is bound to an int and the user types “02” then the textbox will display simply “2”.

I think we need to double-check our binding behavior in such cases where the setter doesn’t preserve the value written to it.

[grokys]

Repoening because this needs investigation.