TextBox.TextInput event is not fired

Describe the bug When typing text into TextBox the event TextInput is not fired.

To Reproduce

1. Generate new project based on “Avalonia .NET Core App”
2. Open MainWindow.axaml and add TextBox with attached event handler to it: <TextBox TextInput="InputElement_OnTextInput" />
3. Define method at MainWindow.axaml.cs:

        private void InputElement_OnTextInput(object? sender, TextInputEventArgs e)
        {
            throw new System.NotImplementedException();
        }

1. Run the project and type some text into textbox
2. Note that text appears in the textbox and no exceptions happen:

Expected behavior Exception is thrown.

Desktop (please complete the following information):

• OS: linux, Pop!_OS 21.04
• Version 0.10.8

Additional information I have tried to debug and found that TextInput event is marked as Handled by TextBox. If we remove Handled = true then user handler is fired.

[grokys]

Our event system is heavily based on WPF (and by extension UWP) and so this behavior comes from there:

• https://stackoverflow.com/questions/1374710/wpf-textbox-not-firing-ontextinput-event
• https://stackoverflow.com/questions/36938437/keydown-event-not-fired-for-textbox-in-uwp

[maxkatz6]

Closing as there are two another related issues.