QuestPDF/QuestPDF.Previewer/FluentWindow.cs

using Avalonia;
using Avalonia.Controls;
using Avalonia.Controls.Primitives;
using Avalonia.Platform;
using Avalonia.Styling;

namespace QuestPDF.Previewer
{
    internal class FluentWindow : Window, IStyleable
    {
        Type IStyleable.StyleKey => typeof(Window);

        public FluentWindow()
        {
            ExtendClientAreaToDecorationsHint = true;
            ExtendClientAreaTitleBarHeightHint = -1;

            TransparencyLevelHint = WindowTransparencyLevel.AcrylicBlur;

            this.GetObservable(WindowStateProperty)
              .Subscribe(x =>
              {
                  PseudoClasses.Set(":maximized", x == WindowState.Maximized);
                  PseudoClasses.Set(":fullscreen", x == WindowState.FullScreen);
              });

            this.GetObservable(IsExtendedIntoWindowDecorationsProperty)
              .Subscribe(x =>
              {
                  if (!x)
                  {
                      SystemDecorations = SystemDecorations.Full;
                      TransparencyLevelHint = WindowTransparencyLevel.Blur;
                  }
              });
        }

        protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
        {
            base.OnApplyTemplate(e);
            ExtendClientAreaChromeHints =
              ExtendClientAreaChromeHints.PreferSystemChrome |
              ExtendClientAreaChromeHints.OSXThickTitleBar;
        }
    }
}