Set the window backgrond and remove it in onCreate().

To have better transistion when launching the app.

bug: 6494653
Change-Id: I0f28796d599931c676c99e8f19a9f34e05018570
diff --git a/src/com/android/gallery3d/app/AbstractGalleryActivity.java b/src/com/android/gallery3d/app/AbstractGalleryActivity.java
index 2c63e34..4ee7403 100644
--- a/src/com/android/gallery3d/app/AbstractGalleryActivity.java
+++ b/src/com/android/gallery3d/app/AbstractGalleryActivity.java
@@ -61,6 +61,7 @@
         super.onCreate(savedInstanceState);
         mOrientationManager = new OrientationManager(this);
         toggleStatusBarByOrientation();
+        getWindow().setBackgroundDrawable(null);
     }
 
     @Override