add Container#isViewedSlot
*/
void close(Player viewer) throws IllegalArgumentException;
+ /**
+ * Returns whether given slot is part of the viewed inventories
+ * but not part of the viewers own inventory.
+ *
+ * <p>Examples for viewed inventory slots:</p>
+ * <p>All the slots of the opened chest and not the player grid below.</p>
+ * <p>The slots of the crafting grid in the opened player inventory.</p>
+ *
+ * @param slot The slot to check.
+ * @return {@code true} when the slot is part of the viewed inventories.
+ */
+ boolean isViewedSlot(Slot slot);
+
}
