WPF设置主窗口

<Application x:Class="testWpf.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    StartupUri="Window2.xaml">
    <Application.Resources>
         
    </Application.Resources>
</Application>

可以在App.xaml文件中设置StartupUri属性来决定哪个窗口是主要窗口