Prev and Next are buttons added.

res/layout/puzzle_view_title.xml

@@ -4,8 +4,19 @@
     android:orientation="horizontal"
 	android:gravity="center_horizontal"
 	android:background="#60404040"
-   	android:layout_height="50dp" 
+   	android:layout_height="48dp" 
    	android:layout_width="match_parent">
+  	<ImageButton
+  		android:src="@drawable/prev"
+		android:scaleType="fitCenter"
+  		android:layout_width="wrap_content"
+  		android:layout_height="20dp"
+		android:layout_gravity="center_vertical"
+		android:layout_weight="0"
+		android:layout_margin="3dp"
+		android:background="#00000000"
+		android:onClick="onPrev"
+  		android:id="@+id/prev_btn"/>
   	<TextView
   		android:text="Level"
   		android:layout_width="wrap_content"
@@ -45,5 +56,16 @@
 		android:background="#00000000"
 		android:onClick="onReset"
   		android:id="@+id/reset_btn"/>
+  	<ImageButton
+  		android:src="@drawable/next"
+		android:scaleType="fitCenter"
+  		android:layout_width="wrap_content"
+  		android:layout_height="20dp"
+		android:layout_gravity="center_vertical"
+		android:layout_weight="0"
+		android:layout_margin="3dp"
+		android:background="#00000000"
+		android:onClick="onNext"
+  		android:id="@+id/next_btn"/>
 </LinearLayout>
 

res/values/strings.xml

@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <resources>
     <string name="app_name">Free Sokoban</string>
+    <string name="app_name_debug">Debug Sokoban</string>
     <string name="menu">Menu</string>
     <string name="play_activity">play_activity</string>
     <string name="btn_start_begin">Begin</string>