binding window height and width and saving properties to file.

MainWindow.xaml

@@ -1,5 +1,4 @@
-    
-<Window
+<Window
     x:Class="ModernWpfPlayground.MainWindow"
     xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
@@ -11,8 +10,8 @@
     xmlns:ui="http://schemas.modernwpf.com/2019"
     x:Name="Window"
     Title="{Binding Title}"
-    Width="1200"
-    Height="600"
+    Width="{Binding WindowWidth, Mode=TwoWay}"
+    Height="{Binding WindowHeight, Mode=TwoWay}"
     d:DataContext="{d:DesignInstance local:MainWindowViewModel}"
     prism:ViewModelLocator.AutoWireViewModel="True"
     ui:ThemeManager.IsThemeAware="True"