NPC sell the equipped item

[chiitus]

Hi guys, i'm editing my server to put online, but i want it perfect!
So i was playing a server that the npc don't 'buy' your equipped item, just that on the backpack
I really want this, someone can help me please?

Thanks adv.

EDIT: I found this on sources:

case ACTION_SELLITEM:
         {
           const ItemType& iit = Item::items[npcState->itemId];
           if(iit.id != 0)
           {
             uint32_t moneyCount = it->intValue;
             if(it->strValue == "|PRICE|")
               moneyCount = npcState->price * npcState->amount;

             int32_t subType = -1;
             if(iit.hasSubType())
               subType = npcState->subType;

             int32_t itemCount = player->__getItemTypeCount(iit.id, subType);
             if(itemCount >= npcState->amount)
             {
               g_game.removeItemOfType(player, iit.id, npcState->amount, subType);
               g_game.addMoney(player, moneyCount, FLAG_NOLIMIT);
             }
           }
           break;
         }

I think instead "g_game.removeItemOfType(player, iit.id, npcState->amount, subType)" i can put a function that remove only backpack's item!