finish auto-hide

QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml

@@ -9,7 +9,7 @@
              x:Name="imagePanel"
              d:DesignHeight="300" d:DesignWidth="300">
     <Grid>
-        <Rectangle>
+        <Rectangle Visibility="{Binding BackgroundVisibility, ElementName=imagePanel}">
             <Rectangle.Fill>
                 <ImageBrush x:Name="backgroundBrush" ImageSource="Resources/background.png" AlignmentY="Top" Viewport="0,0,32,32"
                             ViewportUnits="Absolute" Stretch="UniformToFill" TileMode="Tile" />

QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs

@@ -45,6 +45,7 @@ namespace QuickLook.Plugin.ImageViewer
         private BitmapScalingMode _renderMode = BitmapScalingMode.HighQuality;
         private BitmapSource _source;
         private double _zoomFactor = 1d;
+        private Visibility _backgroundVisibility = Visibility.Visible;
 
         private bool _zoomToFit = true;
 
@@ -88,6 +89,16 @@ namespace QuickLook.Plugin.ImageViewer
             }
         }
 
+        public Visibility BackgroundVisibility
+        {
+            get => _backgroundVisibility;
+            set
+            {
+                _backgroundVisibility = value;
+                OnPropertyChanged();
+            }
+        }
+
         public double MinZoomFactor
         {
             get => _minZoomFactor;

QuickLook.Plugin/QuickLook.Plugin.ImageViewer/Plugin.cs

@@ -64,8 +64,7 @@ namespace QuickLook.Plugin.ImageViewer
                 context.PreferredSize = new Size(1024, 768);
 
             Directory.SetCurrentDirectory(App.AppPath);
-
-            context.AutoHideTitlebar = true;
+            
             context.TitlebarOverlap = true;
         }