test/QualTask/AuthWindow.axaml

<Window 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"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="QualTask.AuthWindow"
        Title="Авторизация">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
            <RowDefinition/>
            <RowDefinition/>
            <RowDefinition/>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        
        <TextBox Grid.Row="1" x:Name="LoginTextBox" Watermark="Логин"/>
        <TextBox Grid.Row="3" x:Name="PasswordTextBox" PasswordChar="#" Watermark="Пароль"/>
        <Button Grid.Row="4" x:Name="AuthButton" Content="Войти" Click="AuthButton_OnClick"/>
        <TextBlock Grid.Row="5" x:Name="ErrorTextBlock" IsVisible="False" Foreground="Red" FontSize="16" 
                   FontWeight="SemiBold" HorizontalAlignment="Center" VerticalAlignment="Center"/>
        <Button Grid.Row="6" x:Name="RegistrationButton" Content="Регистрация" Click="RegistrationButton_OnClick"/>
    </Grid>
</Window>