Demka_kur/SellerWindow.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="Demka_Snova_1.SellerWindow"
        Title="SellerWindow">
<StackPanel>
        <Button Content="сформировать заказ" Click="FormatZakaz_Click"/>
        <Button Content="Выход" Click="Exitka"/>
</StackPanel>
</Window>