Let's have two wallpapers installed so we can test switching.

Kernel/sync.sh

@@ -1,6 +1,6 @@
 rm -vf _fs_contents.lock
 rm -vf _fs_contents
-dd if=/dev/zero of=_fs_contents bs=1M count=8
+dd if=/dev/zero of=_fs_contents bs=1M count=12
 mke2fs _fs_contents
 chown 1000:1000 _fs_contents
 mkdir -vp mnt

WindowServer/WSWindowManager.cpp

@@ -165,7 +165,7 @@ WSWindowManager::WSWindowManager()
 
     {
         LOCKER(m_wallpaper_path.lock());
-        m_wallpaper_path.resource() = "/res/wallpapers/gray-wood.rgb";
+        m_wallpaper_path.resource() = "/res/wallpapers/cool.rgb";
         m_wallpaper = GraphicsBitmap::load_from_file(m_wallpaper_path.resource(), m_screen_rect.size());
     }