diff --git a/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PluginInterface.cs b/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PluginInterface.cs
index 1fb61d8..d79edab 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PluginInterface.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PluginInterface.cs
@@ -24,13 +24,14 @@ namespace QuickLook.Plugin.IPreviewHandlers
                 case ".docx":
                 case ".xls":
                 case ".xlsx":
+                case ".bbb":
                 case ".xlsm":
                 // Visio Viewer will not quit after preview, which cause serious memory issue
                 //case ".vsd":
                 //case ".vsdx":
                 case ".ppt":
                 case ".pptx":
-                    return true;
+                    return PreviewHandlerHost.GetPreviewHandlerGUID(path) != Guid.Empty;
             }
 
             return false;
@@ -47,11 +48,7 @@ namespace QuickLook.Plugin.IPreviewHandlers
             context.ViewerContent = _panel;
             context.Title = Path.GetFileName(path);
 
-            _panel.Loaded += (sender, e) =>
-            {
-                _panel.PreviewFile(path);
-                SetForegroundWindow(new WindowInteropHelper(context.ViewerWindow).Handle);
-            };
+            _panel.PreviewFile(path, context);
 
             context.IsBusy = false;
         }
@@ -63,12 +60,7 @@ namespace QuickLook.Plugin.IPreviewHandlers
             _panel?.Dispose();
             _panel = null;
         }
-
-
-        [DllImport("user32.dll")]
-        [return: MarshalAs(UnmanagedType.Bool)]
-        private static extern bool SetForegroundWindow(IntPtr hWnd);
-
+        
         ~PluginInterface()
         {
             Cleanup();
diff --git a/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PreviewHandlerHost.cs b/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PreviewHandlerHost.cs
index 2c5c22f..e77a770 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PreviewHandlerHost.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PreviewHandlerHost.cs
@@ -61,7 +61,7 @@ namespace QuickLook.Plugin.IPreviewHandlers
         /// </summary>
         /// <param name="filename"></param>
         /// <returns></returns>
-        private Guid GetPreviewHandlerGUID(string filename)
+        public static Guid GetPreviewHandlerGUID(string filename)
         {
             // open the registry key corresponding to the file extension
             var ext = Registry.ClassesRoot.OpenSubKey(Path.GetExtension(filename));
@@ -150,8 +150,4 @@ namespace QuickLook.Plugin.IPreviewHandlers
             }
         }
     }
-
-    #region COM Interop
-
-    #endregion
 }
\ No newline at end of file
diff --git a/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PreviewPanel.xaml.cs b/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PreviewPanel.xaml.cs
index 0c165cb..ee4c6a3 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PreviewPanel.xaml.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.IPreviewHandlers/PreviewPanel.xaml.cs
@@ -1,6 +1,8 @@
 using System;
 using System.Runtime.InteropServices;
 using System.Windows.Controls;
+using System.Windows.Interop;
+using System.Windows.Threading;
 
 namespace QuickLook.Plugin.IPreviewHandlers
 {
@@ -9,7 +11,7 @@ namespace QuickLook.Plugin.IPreviewHandlers
     /// </summary>
     public partial class PreviewPanel : UserControl, IDisposable
     {
-        private PreviewHandlerHost _control = new PreviewHandlerHost();
+        private PreviewHandlerHost _control;
 
         public PreviewPanel()
         {
@@ -25,17 +27,23 @@ namespace QuickLook.Plugin.IPreviewHandlers
             _control = null;
         }
 
-        public void PreviewFile(string file)
+        public void PreviewFile(string file, ContextObject context)
         {
-            _control = new PreviewHandlerHost();
+            Dispatcher.CurrentDispatcher.BeginInvoke(new Action(() =>
+            {
+                _control = new PreviewHandlerHost();
+                presenter.Child = _control;
+                _control.Open(file);
+            }), DispatcherPriority.Render);
 
-            presenter.Child = _control;
-
-            _control.Open(file);
-
-            SetActiveWindow(presenter.Handle);
+            //SetForegroundWindow(new WindowInteropHelper(context.ViewerWindow).Handle);
+            //SetActiveWindow(presenter.Handle);
         }
 
+        [DllImport("user32.dll")]
+        [return: MarshalAs(UnmanagedType.Bool)]
+        private static extern bool SetForegroundWindow(IntPtr hWnd);
+
         [DllImport("user32.dll")]
         [return: MarshalAs(UnmanagedType.Bool)]
         private static extern bool SetActiveWindow(IntPtr hWnd);