feat: fullscreen argument

GSS2.UI.Core/MainWindow.axaml

@@ -6,7 +6,10 @@
     xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:vm="using:GSS2.UI.Core.ViewModels"
     Title="{Binding Title}"
-    x:DataType="vm:MainWindowViewModel">
+    x:DataType="vm:MainWindowViewModel"
+    SystemDecorations="{Binding SystemDecorations}"
+    Topmost="{Binding Topmost}"
+    WindowState="{Binding WindowState}">
 
     <ContentControl x:Name="MainContent" />
 

GSS2.UI.Core/MainWindow.axaml.cs

@@ -1,3 +1,4 @@
+using Avalonia;
 using Avalonia.Controls;
 
 namespace GSS2.UI.Core;
@@ -7,6 +8,9 @@ public partial class MainWindow : Window
     public MainWindow()
     {
         InitializeComponent();
+#if DEBUG
+        this.AttachDevTools();
+#endif
     }
 
     public void SetControl(UserControl control)

GSS2.UI.Core/ViewModels/MainWindowViewModel.cs

@@ -1,3 +1,5 @@
+using Avalonia.Controls;
+
 using CommunityToolkit.Mvvm.ComponentModel;
 
 using Microsoft.Extensions.Logging;
@@ -9,6 +11,9 @@ public partial class MainWindowViewModel : ViewModelBase
     private readonly ILogger<MainWindowViewModel> _logger;
 
     [ObservableProperty] private string _title;
+    [ObservableProperty] private SystemDecorations _systemDecorations;
+    [ObservableProperty] private bool _topmost;
+    [ObservableProperty] private WindowState _windowState;
 
     public MainWindowViewModel(ILogger<MainWindowViewModel> logger)
     {