test/FirstSlice/RoleWindow.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" Height="150" Width="150"
        x:Class="FirstSlice.RoleWindow"
        WindowStartupLocation="CenterOwner"
        Title="RoleWindow">
        
        <Grid>
                <Grid.RowDefinitions>
                        <RowDefinition></RowDefinition>
                        <RowDefinition></RowDefinition>
                </Grid.RowDefinitions>
                
                <TextBox Grid.Row="0" Name="TextRole" Watermark="Роль" VerticalAlignment="Center" Margin="10"/>
                <Button Grid.Row="1" Name="SaveRole" Content="Сохранить роль" Click="OnSaveRoleClick" VerticalAlignment="Center" HorizontalAlignment="Left" Margin="10"></Button>
        </Grid>
</Window>