making only 1 activity the main/launcher, which also fixed the screen flashing on the first transition after changing the theme. nice

app/src/main/AndroidManifest.xml

@@ -16,12 +16,8 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
-        <activity android:name=".ThemeActivity">
-            <intent-filter>
-                <action android:name="android.intent.action.MAIN" />
-
-                <category android:name="android.intent.category.LAUNCHER" />
-            </intent-filter>
+        <activity android:name=".ThemeActivity"
+                  android:parentActivityName=".HomeActivity">
         </activity>
     </application>