move source files

src/UI/MainWindow.axaml.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Threading.Tasks;
+using Avalonia.Controls;
+using Avalonia.Styling;
+using Avalonia.Threading;
+using MercuryConverter.UI.Dialogs;
+using MercuryConverter.UI.Views;
+
+namespace MercuryConverter.UI;
+
+public partial class MainWindow : Window
+{
+    public static MainWindow? Instance { get; private set; }
+    private bool initialShown = false;
+
+    public MainWindow()
+    {
+        Instance = this;
+        InitializeComponent();
+        DataContext = this;
+
+        // Force dark mode in designer
+        if (Design.IsDesignMode)
+        {
+            RequestedThemeVariant = ThemeVariant.Dark;
+        }
+
+        // Setup tab views
+        SelectionControl.Content = new Selection();
+
+        // Show dialog on startup
+        Activated += OnActivated;
+    }
+
+    private void OnActivated(object? sender, EventArgs e)
+    {
+        if (initialShown) return;
+        initialShown = true;
+
+        Dialog.DialogContent = new Welcome().Content;
+        Dialog.IsOpen = true;
+    }
+
+    public void OpenDataHandler()
+    {
+        Dialog.IsOpen = true;
+        Dialog.DialogContent = new DataScanning().Content;
+    }
+
+    public void OpenDataHOWTO()
+    {
+        var launcher = GetTopLevel(this)?.Launcher;
+        if (launcher != null)
+        {
+            launcher.LaunchUriAsync(new Uri("https://github.com/muskit/MercuryConverter/blob/main/HOWTO.md"));
+        }
+    }
+}