WPF GridSplitter最好设置HorizontalAlignment和VerticalAlignment，否则不可以左右移动

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window5" Height="300" Width="300">
   
       
       
           
           
           
       


       
        HorizontalAlignment="Center" VerticalAlignment="Stretch" Background="Wheat"/>