diff --git a/QuickLook/Converters/BooleanToVisibilityCollapsedConverter.cs b/QuickLook/Converters/BooleanTrueToVisibilityCollapsedConverter.cs
similarity index 85%
rename from QuickLook/Converters/BooleanToVisibilityCollapsedConverter.cs
rename to QuickLook/Converters/BooleanTrueToVisibilityCollapsedConverter.cs
index 3bdf71f..bd3bb62 100644
--- a/QuickLook/Converters/BooleanToVisibilityCollapsedConverter.cs
+++ b/QuickLook/Converters/BooleanTrueToVisibilityCollapsedConverter.cs
@@ -22,16 +22,16 @@ using System.Windows.Data;
 
 namespace QuickLook.Converters
 {
-    public sealed class BooleanToVisibilityCollapsedConverter : DependencyObject, IValueConverter
+    public sealed class BooleanTrueToVisibilityCollapsedConverter : DependencyObject, IValueConverter
     {
         public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
         {
             if (value == null)
-                return Visibility.Visible;
+                return Visibility.Collapsed;
 
             var v = (bool) value;
 
-            return v ? Visibility.Visible : Visibility.Collapsed;
+            return v ? Visibility.Collapsed : Visibility.Visible;
         }
 
         object IValueConverter.ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
diff --git a/QuickLook/MainWindowTransparent.xaml b/QuickLook/MainWindowTransparent.xaml
index 6e37662..3d84e17 100644
--- a/QuickLook/MainWindowTransparent.xaml
+++ b/QuickLook/MainWindowTransparent.xaml
@@ -18,13 +18,15 @@
     <Window.Resources>
         <converters:BooleanToResizeModeConverter x:Key="BooleanToResizeModeConverter" />
         <converters:BooleanToResizeBorderThicknessConverter x:Key="BooleanToResizeBorderThicknessConverter" />
+        <converters:BooleanTrueToVisibilityCollapsedConverter x:Key="BooleanTrueToVisibilityCollapsedConverter" />
     </Window.Resources>
     <Window.ResizeMode>
         <Binding Converter="{StaticResource BooleanToResizeModeConverter}" ElementName="mainWindow"
                  Path="ContextObject.CanResize" />
     </Window.ResizeMode>
     <WindowChrome.WindowChrome>
-        <WindowChrome x:Name="chrome" ResizeBorderThickness="{Binding ContextObject.CanResize, Converter={StaticResource BooleanToResizeBorderThicknessConverter}, ElementName=mainWindow}"
+        <WindowChrome x:Name="chrome"
+                      ResizeBorderThickness="{Binding ContextObject.CanResize, Converter={StaticResource BooleanToResizeBorderThicknessConverter}, ElementName=mainWindow}"
                       UseAeroCaptionButtons="False" />
     </WindowChrome.WindowChrome>
     <Border x:Name="windowBorder" BorderThickness="1" BorderBrush="#FF7B7B7B">
@@ -58,12 +60,13 @@
                 <DockPanel x:Name="titlebar" Height="28" Dock="Top">
                     <fa:ImageAwesome DockPanel.Dock="Right" x:Name="buttonCloseWindow" Icon="TimesCircle"
                                      WindowChrome.IsHitTestVisibleInChrome="True"
-                                     Height="15" Margin="10,0" Foreground="Gray"
+                                     Width="15" Height="15" Margin="10,0" Foreground="Gray"
                                      Cursor="Hand" />
                     <Button x:Name="buttonOpenWith" DockPanel.Dock="Right" Content="Open with..." Height="20"
                             Margin="10,0,0,0" Padding="5,0"
                             Focusable="False" Cursor="Hand"
                             Background="#E5EEEEEE" BorderBrush="#E59A9A9A"
+                            Visibility="{Binding Pinned,ElementName=mainWindow,Converter={StaticResource BooleanTrueToVisibilityCollapsedConverter}}"
                             WindowChrome.IsHitTestVisibleInChrome="True" Foreground="#FF404040">
                         <Button.ContentTemplate>
                             <DataTemplate>
@@ -71,6 +74,31 @@
                             </DataTemplate>
                         </Button.ContentTemplate>
                     </Button>
+                    <fa:ImageAwesome DockPanel.Dock="Left" x:Name="buttonPin" Icon="ThumbTack"
+                                     WindowChrome.IsHitTestVisibleInChrome="True"
+                                     Width="14" Height="14" Margin="10,0"
+                                     Cursor="Hand">
+                        <fa:ImageAwesome.Style>
+                            <Style TargetType="{x:Type fa:ImageAwesome}">
+                                <Setter Property="Foreground" Value="Gray" />
+                                <Setter Property="LayoutTransform">
+                                    <Setter.Value>
+                                        <RotateTransform Angle="-45" />
+                                    </Setter.Value>
+                                </Setter>
+                                <Style.Triggers>
+                                    <DataTrigger Binding="{Binding Pinned, ElementName=mainWindow}" Value="True">
+                                        <Setter Property="Foreground" Value="Black" />
+                                        <Setter Property="LayoutTransform">
+                                            <Setter.Value>
+                                                <RotateTransform Angle="0" />
+                                            </Setter.Value>
+                                        </Setter>
+                                    </DataTrigger>
+                                </Style.Triggers>
+                            </Style>
+                        </fa:ImageAwesome.Style>
+                    </fa:ImageAwesome>
                     <!-- set grid.background colour makes it clickable -->
                     <Grid x:Name="titleArea" Background="Transparent">
                         <TextBlock Text="{Binding ContextObject.Title, ElementName=mainWindow}" FontSize="14"
diff --git a/QuickLook/MainWindowTransparent.xaml.cs b/QuickLook/MainWindowTransparent.xaml.cs
index d8827a0..d206772 100644
--- a/QuickLook/MainWindowTransparent.xaml.cs
+++ b/QuickLook/MainWindowTransparent.xaml.cs
@@ -16,13 +16,16 @@
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 using System;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.IO;
+using System.Runtime.CompilerServices;
 using System.Runtime.ExceptionServices;
 using System.Windows;
 using System.Windows.Input;
 using System.Windows.Media;
 using System.Windows.Threading;
+using QuickLook.Annotations;
 using QuickLook.Helpers;
 using QuickLook.Helpers.BlurLibrary;
 using QuickLook.Plugin;
@@ -32,8 +35,10 @@ namespace QuickLook
     /// <summary>
     ///     Interaction logic for MainWindowTransparent.xaml
     /// </summary>
-    public partial class MainWindowTransparent : Window
+    public partial class MainWindowTransparent : Window, INotifyPropertyChanged
     {
+        private bool _pinned;
+
         internal MainWindowTransparent()
         {
             // this object should be initialized before loading UI components, because many of which are binding to it.
@@ -41,8 +46,7 @@ namespace QuickLook
 
             InitializeComponent();
 
-            FontFamily =
-                new FontFamily(TranslationHelper.GetString("UI_FontFamily", failsafe: "Segoe UI"));
+            FontFamily = new FontFamily(TranslationHelper.GetString("UI_FontFamily", failsafe: "Segoe UI"));
 
             SourceInitialized += (sender, e) =>
             {
@@ -50,18 +54,43 @@ namespace QuickLook
                     BlurWindow.EnableWindowBlur(this);
             };
 
+            buttonPin.MouseLeftButtonUp += (sender, e) =>
+            {
+                if (Pinned) return;
+                Pinned = true;
+                buttonOpenWith.Visibility = Visibility.Collapsed;
+                ViewWindowManager.GetInstance().ForgetCurrentWindow();
+            };
+
             buttonCloseWindow.MouseLeftButtonUp += (sender, e) =>
-                ViewWindowManager.GetInstance().ClosePreview();
+            {
+                if (Pinned)
+                    BeginClose();
+                else
+                    ViewWindowManager.GetInstance().ClosePreview();
+            };
 
             buttonOpenWith.Click += (sender, e) =>
                 ViewWindowManager.GetInstance().RunAndClosePreview();
         }
 
+        public bool Pinned
+        {
+            get => _pinned;
+            private set
+            {
+                _pinned = value;
+                OnPropertyChanged();
+            }
+        }
+
         public string PreviewPath { get; private set; }
         public IViewer Plugin { get; private set; }
 
         public ContextObject ContextObject { get; private set; }
 
+        public event PropertyChangedEventHandler PropertyChanged;
+
         internal void RunAndHide()
         {
             if (string.IsNullOrEmpty(PreviewPath))
@@ -181,10 +210,8 @@ namespace QuickLook
 
             buttonOpenWith.Content = isExe == null
                 ? Directory.Exists(PreviewPath)
-                    ? string.Format(TranslationHelper.GetString("MW_BrowseFolder"),
-                        Path.GetFileName(PreviewPath))
-                    : string.Format(TranslationHelper.GetString("MW_Open"),
-                        Path.GetFileName(PreviewPath))
+                    ? string.Format(TranslationHelper.GetString("MW_BrowseFolder"), Path.GetFileName(PreviewPath))
+                    : string.Format(TranslationHelper.GetString("MW_Open"), Path.GetFileName(PreviewPath))
                 : isExe == true
                     ? string.Format(TranslationHelper.GetString("MW_Run"), appFriendlyName)
                     : string.Format(TranslationHelper.GetString("MW_OpenWith"), appFriendlyName);
@@ -202,5 +229,20 @@ namespace QuickLook
 
             ProcessHelper.PerformAggressiveGC();
         }
+
+        internal void BeginClose()
+        {
+            UnloadPlugin();
+
+            Close();
+
+            ProcessHelper.PerformAggressiveGC();
+        }
+
+        [NotifyPropertyChangedInvocator]
+        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
+        {
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+        }
     }
 }
\ No newline at end of file
diff --git a/QuickLook/QuickLook.csproj b/QuickLook/QuickLook.csproj
index 9b7f2b3..9d3542a 100644
--- a/QuickLook/QuickLook.csproj
+++ b/QuickLook/QuickLook.csproj
@@ -107,7 +107,7 @@
       <Link>Properties\GitVersion.cs</Link>
     </Compile>
     <Compile Include="Converters\BooleanToResizeModeConverter.cs" />
-    <Compile Include="Converters\BooleanToVisibilityCollapsedConverter.cs" />
+    <Compile Include="Converters\BooleanTrueToVisibilityCollapsedConverter.cs" />
     <Compile Include="Converters\BooleanToResizeBorderThicknessConverter.cs" />
     <Compile Include="FocusMonitor.cs" />
     <Compile Include="Helpers\AutoStartupHelper.cs" />
diff --git a/QuickLook/ViewWindowManager.cs b/QuickLook/ViewWindowManager.cs
index 05e6ae6..acc3ccf 100644
--- a/QuickLook/ViewWindowManager.cs
+++ b/QuickLook/ViewWindowManager.cs
@@ -31,18 +31,18 @@ namespace QuickLook
     {
         private static ViewWindowManager _instance;
 
-        private readonly MainWindowNoTransparent _viewWindowNoTransparent;
-        private readonly MainWindowTransparent _viewWindowTransparentTransparent;
+        private MainWindowNoTransparent _viewWindowNoTransparent;
+        private MainWindowTransparent _viewWindowTransparent;
         private MainWindowTransparent _currentMainWindow;
 
         private string _path = string.Empty;
 
         internal ViewWindowManager()
         {
-            _viewWindowTransparentTransparent = new MainWindowTransparent();
+            _viewWindowTransparent = new MainWindowTransparent();
             _viewWindowNoTransparent = new MainWindowNoTransparent();
 
-            _currentMainWindow = _viewWindowTransparentTransparent;
+            _currentMainWindow = _viewWindowTransparent;
         }
 
         public void Dispose()
@@ -172,6 +172,18 @@ namespace QuickLook
                 FocusMonitor.GetInstance().Heartbeat -= SwitchPreviewRemoteInvoke;
             }
         }
+        
+        internal void ForgetCurrentWindow()
+        {
+            StopFocusMonitor();
+
+            if (ReferenceEquals(_currentMainWindow, _viewWindowTransparent))
+                _viewWindowTransparent=new MainWindowTransparent();
+            else
+                _viewWindowNoTransparent = new MainWindowNoTransparent();
+
+            _currentMainWindow = _viewWindowTransparent;
+        }
 
         internal bool InvokeViewer(string path = null, bool closeIfSame = false)
         {
@@ -206,7 +218,7 @@ namespace QuickLook
             // switch window
             var oldWindow = _currentMainWindow;
             _currentMainWindow = matchedPlugin.AllowsTransparency
-                ? _viewWindowTransparentTransparent
+                ? _viewWindowTransparent
                 : _viewWindowNoTransparent;
             if (!ReferenceEquals(oldWindow, _currentMainWindow))
                 oldWindow.BeginHide();