Test/Tren/MainWindow.xaml

<Window x:Class="Tren.MainWindow"
        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:Tren"
        mc:Ignorable="d"
        Title="Название приложения" Height="700" Width="1000" MinHeight="450" MinWidth="800">
    <Grid>
        <Frame x:Name="MainFrame" NavigationUIVisibility="Hidden"/>
    </Grid>
</Window>