for_vika/praktika_2/Menu.xaml

<Window x:Class="praktika_2.Menu"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        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:local="clr-namespace:praktika_2"
        mc:Ignorable="d"
        Title="Главное меню" Height="250" Width="250" WindowStartupLocation="CenterScreen">
    <Grid Background="#00BFFF">
        <Button x:Name="G" Content="Ввод данных поступления" Margin="0,10,0,169" HorizontalAlignment="Center" Width="158" Click="G_Click"/>
        <Button x:Name="a" Content="Список ценных МЦ" Margin="0,85,0,94" HorizontalAlignment="Center" Width="158" Click="a_Click"/>
        <Button x:Name="A3" Content="Общий список поступивших МЦ" Margin="0,156,0,23" HorizontalAlignment="Center" Width="158" Click="a3_Click"/>

    </Grid>
</Window>