Since you didn't have this,
PHP:
public static byte[] changeBackground(List<Pair<String, Integer>> backgrounds) {
MaplePacketLittleEndianWriter mplew = new MaplePacketLittleEndianWriter();
mplew.writeShort(SendPacketOpcode.CHANGE_BACKGROUND.getValue());
mplew.write(backgrounds.size()); //number of bgs
for (Pair<String, Integer> background : backgrounds) {
mplew.writeMapleAsciiString(background.getLeft());
mplew.write(background.getRight());
}
return mplew.getPacket();
}
List<Pair<String, Integer>> backgrounds = new LinkedList<>();
backgrounds.add(new Pair<>("20120808", 0)); //remove dual blade background so it shows red leaf high
backgrounds.add(new Pair<>("20120815", 0)); //remove red leaf high background so it shows mihile
Edit:
backgrounds.add(new Pair<>("20120905", 0));
to remove mihile background so it shows chinese new year background (dragonzzzzzz)