Gallery2: Disable dummy starting window

* Improve launch UX

Change-Id: Ib181fe674220b893de339fe81ff500ac80996523
diff --git a/res/values/styles.xml b/res/values/styles.xml
index 1bc7fbe..dafe0d9 100644
--- a/res/values/styles.xml
+++ b/res/values/styles.xml
@@ -316,6 +316,7 @@
     </style>
 
     <style name="AppTheme" parent="Theme.AppCompat.Light">
+        <item name="android:windowDisablePreview">true</item>
         <item name="android:windowDrawsSystemBarBackgrounds">true</item>
         <item name="android:windowBackground">@android:color/black</item>
         <item name="android:statusBarColor">@android:color/transparent</item>