Enable Proguard on Launcher2.
diff --git a/proguard.flags b/proguard.flags
new file mode 100644
index 0000000..b8aeff7
--- /dev/null
+++ b/proguard.flags
@@ -0,0 +1,4 @@
+-keep class com.android.launcher2.Launcher {
+  public void previousScreen(android.view.View);
+  public void nextScreen(android.view.View);
+}