fix: failed get default font on some Linux distro (sourcegit-scm#447)

Author: love-linger

src/App.axaml.cs

@@ -75,7 +75,7 @@ public override void Initialize()
             AvaloniaXamlLoader.Load(this);
 
             var pref = ViewModels.Preference.Instance;
-            pref.PropertyChanged += (_1, _2) => pref.Save();
+            pref.PropertyChanged += (_, _) => pref.Save();
 
             SetLocale(pref.Locale);
             SetTheme(pref.Theme, pref.ThemeOverrides);

src/Native/Linux.cs

@@ -5,6 +5,7 @@
 using System.Runtime.Versioning;
 
 using Avalonia;
+using Avalonia.Media;
 
 namespace SourceGit.Native
 {
@@ -36,6 +37,12 @@ public Linux()
 
         public void SetupApp(AppBuilder builder)
         {
+            // Fix issue https://github.com/sourcegit-scm/sourcegit/issues/447
+            builder.With(new FontManagerOptions()
+            {
+                DefaultFamilyName = "fonts:SourceGit#JetBrains Mono",
+            });
+            
             builder.With(new X11PlatformOptions()
             {
                 EnableIme = true,

src/Resources/Themes.axaml

@@ -99,6 +99,6 @@
   <SolidColorBrush x:Key="Brush.Link" Color="{DynamicResource Color.Link}"/>
 
   <FontFamily x:Key="Fonts.Default">$Default</FontFamily>
-  <FontFamily x:Key="Fonts.Monospace">fonts:SourceGit#JetBrains Mono,$Default</FontFamily>
-  <FontFamily x:Key="Fonts.Primary">fonts:SourceGit#JetBrains Mono,$Default</FontFamily>
+  <FontFamily x:Key="Fonts.Monospace">fonts:SourceGit#JetBrains Mono</FontFamily>
+  <FontFamily x:Key="Fonts.Primary">fonts:SourceGit#JetBrains Mono</FontFamily>
 </ResourceDictionary>