Kapcha/shkola/Views/avtorizacia.axaml

<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="clr-namespace:shkola.ViewModels"
			       x:DataType="vm:MainWindowViewModel"
             mc:Ignorable="d" d:DesignWidth="600" d:DesignHeight="450"
             x:Class="shkola.avtorizacia">
  <StackPanel Margin="15" VerticalAlignment="Center">
      <TextBox Width="400" Watermark="Введите логин" TextAlignment="Center" IsEnabled="{Binding LP.Enable}" Text = "{Binding LP.GetSetLogin}" Name="Login"/>
      <TextBox Margin="0 10 0 0" Width="400" IsEnabled="{Binding LP.Enable}" TextAlignment="Center" Text="{Binding LP.GetSetPass}" PasswordChar="*" Name="Pass" Watermark="Введите пароль"/>
      <StackPanel IsVisible="{Binding LP.Visibility}">
        <TextBlock Margin="0 20 0 0" HorizontalAlignment="Center">CAPTCHA</TextBlock>
        <TextBox Width="400"  Watermark="Введите капчу" TextAlignment="Center" Text="{Binding LP.CapText}"/>
        <UserControl Content="{Binding LP.Capcha}"></UserControl>
    </StackPanel>
    <Button Margin="0 10 0 0" Width="400" HorizontalAlignment="Center" IsEnabled="{Binding LP.Enable}" Command="{Binding toCalculator}">Войти</Button>
  </StackPanel>
</UserControl>