Implements opening containers from items with and without a block context.

src/api/java/appeng/api/implementations/guiobjects/IGuiItem.java

@@ -28,6 +28,8 @@ import net.minecraft.item.ItemStack;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
 
+import javax.annotation.Nullable;
+
 
 /**
  * Implemented on Item objects, to return objects used to manage, and interact
@@ -35,6 +37,14 @@ import net.minecraft.world.World;
  */
 public interface IGuiItem
 {
-
-	IGuiItemObject getGuiObject( ItemStack is, World world, BlockPos pos );
+	/**
+	 *
+	 * @param is The item used to open the container.
+	 * @param playerInventorySlot The slot in the player's inventory the item is in.
+	 * @param world The world the player is in.
+	 * @param pos If the item was used on a block in the world, has that block's position. Null if no block was targetted.
+	 * @return Null if no GUI object is available.
+	 */
+	@Nullable
+	IGuiItemObject getGuiObject( ItemStack is, int playerInventorySlot, World world, @Nullable BlockPos pos );
 }