No mistake drops anymore

src/de/steamwar/fightsystem/listener/InventoryListener.java

@@ -8,6 +8,7 @@ import org.bukkit.event.inventory.InventoryClickEvent;
 import org.bukkit.event.inventory.InventoryDragEvent;
 import org.bukkit.event.inventory.InventoryPickupItemEvent;
 import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.event.player.PlayerDropItemEvent;
 import org.bukkit.inventory.Inventory;
 import org.bukkit.inventory.ItemStack;
 
@@ -61,4 +62,9 @@ public class InventoryListener extends BasicListener {
     public void onDropPickup(InventoryPickupItemEvent e){
         e.setCancelled(true);
     }
+
+    @EventHandler
+    public void onDropping(PlayerDropItemEvent e){
+        e.setCancelled(true);
+    }
 }