diff --git a/eco-api/src/main/java/com/willfp/eco/core/gui/slot/FillerSlot.java b/eco-api/src/main/java/com/willfp/eco/core/gui/slot/FillerSlot.java
index 4ae98a35..d282c554 100644
--- a/eco-api/src/main/java/com/willfp/eco/core/gui/slot/FillerSlot.java
+++ b/eco-api/src/main/java/com/willfp/eco/core/gui/slot/FillerSlot.java
@@ -30,4 +30,9 @@ public class FillerSlot implements Slot {
     public ItemStack getItemStack(@NotNull final Player player) {
         return itemStack;
     }
+
+    @Override
+    public boolean isCaptive() {
+        return false;
+    }
 }
diff --git a/eco-api/src/main/java/com/willfp/eco/core/gui/slot/Slot.java b/eco-api/src/main/java/com/willfp/eco/core/gui/slot/Slot.java
index 1689d55e..94ec8594 100644
--- a/eco-api/src/main/java/com/willfp/eco/core/gui/slot/Slot.java
+++ b/eco-api/src/main/java/com/willfp/eco/core/gui/slot/Slot.java
@@ -19,6 +19,13 @@ public interface Slot {
      */
     ItemStack getItemStack(@NotNull Player player);
 
+    /**
+     * If the slot is captive. (Can items be placed in it).
+     *
+     * @return If captive.
+     */
+    boolean isCaptive();
+
     /**
      * Create a builder for an ItemStack.
      *
diff --git a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/EcoGUIFactory.kt b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/EcoGUIFactory.kt
index 553b8367..64e0d50c 100644
--- a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/EcoGUIFactory.kt
+++ b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/EcoGUIFactory.kt
@@ -3,14 +3,12 @@ package com.willfp.eco.internal.gui
 import com.willfp.eco.core.gui.GUIFactory
 import com.willfp.eco.core.gui.menu.MenuBuilder
 import com.willfp.eco.core.gui.slot.SlotBuilder
+import com.willfp.eco.core.gui.slot.SlotProvider
 import com.willfp.eco.internal.gui.menu.EcoMenuBuilder
 import com.willfp.eco.internal.gui.slot.EcoSlotBuilder
-import org.bukkit.entity.Player
-import org.bukkit.inventory.ItemStack
-import java.util.function.Function
 
 class EcoGUIFactory : GUIFactory {
-    override fun createSlotBuilder(provider: Function<Player, ItemStack>): SlotBuilder {
+    override fun createSlotBuilder(provider: SlotProvider): SlotBuilder {
         return EcoSlotBuilder(provider)
     }
 
diff --git a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoCaptivatorSlot.kt b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoCaptivatorSlot.kt
index ceea0d9d..fc2190bd 100644
--- a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoCaptivatorSlot.kt
+++ b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoCaptivatorSlot.kt
@@ -20,4 +20,8 @@ class EcoCaptivatorSlot : EcoSlot(
             event.isCancelled = false
         }
     }
+
+    override fun isCaptive(): Boolean {
+        return true
+    }
 }
\ No newline at end of file
diff --git a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoSlot.kt b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoSlot.kt
index 559e8c6f..a0d19949 100644
--- a/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoSlot.kt
+++ b/eco-core/core-backend/src/main/kotlin/com/willfp/eco/internal/gui/slot/EcoSlot.kt
@@ -37,4 +37,8 @@ open class EcoSlot(
     override fun getItemStack(player: Player): ItemStack {
         return provider.provide(player, MenuHandler.getMenu(player.openInventory.topInventory)!!)
     }
+
+    override fun isCaptive(): Boolean {
+        return false
+    }
 }
\ No newline at end of file
diff --git a/eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/gui/GUIListener.kt b/eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/gui/GUIListener.kt
index 3c57d233..d3a3402e 100644
--- a/eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/gui/GUIListener.kt
+++ b/eco-core/core-plugin/src/main/kotlin/com/willfp/eco/spigot/gui/GUIListener.kt
@@ -13,6 +13,7 @@ import org.bukkit.entity.Player
 import org.bukkit.event.EventHandler
 import org.bukkit.event.EventPriority
 import org.bukkit.event.Listener
+import org.bukkit.event.inventory.ClickType
 import org.bukkit.event.inventory.InventoryClickEvent
 import org.bukkit.event.inventory.InventoryCloseEvent
 
@@ -49,6 +50,31 @@ class GUIListener(plugin: EcoPlugin) : PluginDependent<EcoPlugin>(plugin), Liste
         plugin.scheduler.runLater({ Bukkit.getLogger().info(menu.getCaptiveItems(player).toString()) }, 1)
     }
 
+    @EventHandler
+    fun handleShiftClick(event: InventoryClickEvent) {
+        if (!(event.click == ClickType.SHIFT_RIGHT || event.click == ClickType.SHIFT_LEFT)) {
+            return
+        }
+
+        val player = event.whoClicked
+        if (player !is Player) {
+            return
+        }
+
+        val inv = player.openInventory.topInventory
+
+        val menu = MenuHandler.getMenu(inv) ?: return
+
+        val rowColumn = MenuUtils.convertSlotToRowColumn(inv.firstEmpty())
+        val row = rowColumn.first!!
+        val column = rowColumn.second!!
+        val slot = menu.getSlot(row, column)
+
+        if (!slot.isCaptive) {
+            event.isCancelled = true
+        }
+    }
+
     @EventHandler(priority = EventPriority.HIGH)
     fun handleClose(event: InventoryCloseEvent) {
         val player = event.player