diff --git a/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUI.kt b/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUI.kt
index 154ea37c..53b4c266 100644
--- a/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUI.kt
+++ b/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUI.kt
@@ -41,7 +41,9 @@ class InventoryGUIHolder(kSpigot: KSpigot) : AutoCloseable {
 
         kSpigot.listen<InventoryClickEvent> {
 
-            val inv = registered.find { search -> search.isThisInv(it.inventory) } ?: return@listen
+            val clickedInv = it.clickedInventory ?: return@listen
+
+            val inv = registered.find { search -> search.isThisInv(clickedInv) } ?: return@listen
             val invPage = inv.currentPageInt
 
             val slot = inv.data.pages[invPage]?.slots?.get(it.slot)
@@ -74,13 +76,13 @@ class InventoryGUIClickEvent<T : ForInventory>(
 private const val DEFAULT_PAGE = 1
 
 class InventoryGUIData<T : ForInventory>(
-        val plugin: KSpigot,
-        val inventoryType: InventoryType<T>,
-        val title: String?,
-        internal val pages: Map<Int, InventoryGUIPage<T>>,
-        val transitionTo: InventoryGUIPageChangeEffect?,
-        val transitionFrom: InventoryGUIPageChangeEffect?,
-        internal val generalOnClick: ((InventoryGUIClickEvent<T>) -> Unit)?
+    val plugin: KSpigot,
+    val inventoryType: InventoryType<T>,
+    val title: String?,
+    internal val pages: Map<Int, InventoryGUIPage<T>>,
+    val transitionTo: InventoryChangeEffect?,
+    val transitionFrom: InventoryChangeEffect?,
+    internal val generalOnClick: ((InventoryGUIClickEvent<T>) -> Unit)?
 )
 
 abstract class InventoryGUI<T : ForInventory>(
@@ -93,7 +95,7 @@ abstract class InventoryGUI<T : ForInventory>(
 
     internal abstract val bukkitInventory: Inventory
 
-    internal abstract fun loadPageUnsafe(page: InventoryGUIPage<*>?, offsetHorizontally: Int = 0, offsetVertically: Int = 0)
+    internal abstract fun loadPageUnsafe(page: InventoryGUIPage<*>, offsetHorizontally: Int = 0, offsetVertically: Int = 0)
     internal abstract fun loadPageUnsafe(page: Int, offsetHorizontally: Int = 0, offsetVertically: Int = 0)
 
     /**
@@ -144,9 +146,7 @@ class InventoryGUIShared<T : ForInventory>(
 
     override fun isThisInv(inventory: Inventory) = inventory == bukkitInventory
 
-    override fun loadPageUnsafe(page: InventoryGUIPage<*>?, offsetHorizontally: Int, offsetVertically: Int) {
-
-        if (page == null) return
+    override fun loadPageUnsafe(page: InventoryGUIPage<*>, offsetHorizontally: Int, offsetVertically: Int) {
 
         val ifOffset = offsetHorizontally != 0 || offsetVertically != 0
 
@@ -204,8 +204,8 @@ class InventoryGUIShared<T : ForInventory>(
 }
 
 class InventoryGUIPage<T : ForInventory>(
-        val number: Int,
-        internal val slots: Map<Int, InventoryGUISlot<T>>,
-        val transitionTo: InventoryGUIPageChangeEffect?,
-        val transitionFrom: InventoryGUIPageChangeEffect?
+    val number: Int,
+    internal val slots: Map<Int, InventoryGUISlot<T>>,
+    val transitionTo: PageChangeEffect?,
+    val transitionFrom: PageChangeEffect?
 )
\ No newline at end of file
diff --git a/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIBuilder.kt b/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIBuilder.kt
index c871aafb..ae50709e 100644
--- a/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIBuilder.kt
+++ b/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIBuilder.kt
@@ -17,8 +17,8 @@ class InventoryGUIBuilder<T : ForInventory>(
 
     var title: String = ""
 
-    var transitionTo: InventoryGUIPageChangeEffect? = null
-    var transitionFrom: InventoryGUIPageChangeEffect? = null
+    var transitionTo: InventoryChangeEffect? = null
+    var transitionFrom: InventoryChangeEffect? = null
 
     private val guiSlots = HashMap<Int, InventoryGUIPage<T>>()
 
@@ -50,8 +50,8 @@ class InventoryGUIPageBuilder<T : ForInventory>(
 
     private val guiSlots = HashMap<Int, InventoryGUISlot<T>>()
 
-    var transitionTo: InventoryGUIPageChangeEffect? = null
-    var transitionFrom: InventoryGUIPageChangeEffect? = null
+    var transitionTo: PageChangeEffect? = null
+    var transitionFrom: PageChangeEffect? = null
 
     internal fun build() = InventoryGUIPage(page, guiSlots, transitionTo, transitionFrom)
 
@@ -117,7 +117,7 @@ class InventoryGUIPageBuilder<T : ForInventory>(
      * By pressing this button, the player switches to another
      * InventoryGUI. The transition effect is applied.
      */
-    fun changeGUI(slots: InventorySlotCompound<T>, itemStack: ItemStack, newGUI: InventoryGUI<*>, newPage: Int? = null, onChange: ((InventoryGUIClickEvent<T>) -> Unit)? = null)
+    fun changeGUI(slots: InventorySlotCompound<T>, itemStack: ItemStack, newGUI: () -> InventoryGUI<*>, newPage: Int? = null, onChange: ((InventoryGUIClickEvent<T>) -> Unit)? = null)
         = defineSlots(slots, InventoryGUIButtonInventoryChange(
             InventoryGUIElementData(itemStack),
             newGUI,
diff --git a/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIElements.kt b/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIElements.kt
index 0f586cc8..5be704da 100644
--- a/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIElements.kt
+++ b/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIElements.kt
@@ -61,7 +61,7 @@ class InventoryGUIButtonPageChange<T : ForInventory>(
         if (newPage != null) {
 
             val effect = (newPage.transitionTo ?: currentPage.transitionFrom)
-                    ?: InventoryGUIPageChangeEffect.INSTANT
+                    ?: PageChangeEffect.INSTANT
 
             it.gui.changePage(effect, currentPage, newPage)
 
@@ -73,18 +73,20 @@ class InventoryGUIButtonPageChange<T : ForInventory>(
 
 class InventoryGUIButtonInventoryChange<T : ForInventory>(
         inventoryGUIElementData: InventoryGUIElementData,
-        changeToGUI: InventoryGUI<*>,
+        changeToGUICallback: () -> InventoryGUI<*>,
         changeToPageInt: Int?,
         onChange: ((InventoryGUIClickEvent<T>) -> Unit)?
 )
     : InventoryGUIButton<T>(inventoryGUIElementData, {
 
+        val changeToGUI = changeToGUICallback.invoke()
+
         val effect = (changeToGUI.data.transitionTo ?: it.gui.data.transitionFrom)
-                ?: InventoryGUIPageChangeEffect.INSTANT
+                ?: InventoryChangeEffect.INSTANT
 
         val changeToPage = changeToGUI.getPage(changeToPageInt) ?: changeToGUI.currentPage
 
-        changeToGUI.changePage(effect, it.gui.currentPage, changeToPage)
+        changeToGUI.changeGUI(effect, it.gui.currentPage, changeToPage)
 
         it.bukkitEvent.whoClicked.openGUI(changeToGUI)
 
diff --git a/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIPageChange.kt b/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIPageChange.kt
index f8c4b6bb..edbbb3b8 100644
--- a/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIPageChange.kt
+++ b/src/main/kotlin/net/axay/kspigot/inventory/InventoryGUIPageChange.kt
@@ -23,7 +23,7 @@ abstract class InventoryGUIPageChangeCalculator {
 
 }
 
-enum class InventoryGUIPageChangeEffect {
+enum class PageChangeEffect {
     INSTANT,
     SLIDE_HORIZONTALLY,
     SLIDE_VERTICALLY,
@@ -31,16 +31,26 @@ enum class InventoryGUIPageChangeEffect {
     SWIPE_VERTICALLY,
 }
 
-internal fun InventoryGUI<*>.changePage(effect: InventoryGUIPageChangeEffect, fromPage: InventoryGUIPage<*>?, toPage: InventoryGUIPage<*>?) {
+enum class InventoryChangeEffect(
+    val effect: PageChangeEffect
+) {
+    INSTANT(PageChangeEffect.INSTANT)
+}
 
-    val fromPageInt = fromPage?.number ?: 0
-    val toPageInt = toPage?.number ?: 0
+internal fun InventoryGUI<*>.changePage(
+    effect: PageChangeEffect,
+    fromPage: InventoryGUIPage<*>,
+    toPage: InventoryGUIPage<*>
+) {
+
+    val fromPageInt = fromPage.number
+    val toPageInt = toPage.number
 
     when (effect) {
 
-        InventoryGUIPageChangeEffect.INSTANT -> loadPageUnsafe(toPage)
+        PageChangeEffect.INSTANT -> loadPageUnsafe(toPage)
 
-        InventoryGUIPageChangeEffect.SLIDE_HORIZONTALLY -> {
+        PageChangeEffect.SLIDE_HORIZONTALLY -> {
 
             val width = data.inventoryType.dimensions.width
 
@@ -56,7 +66,7 @@ internal fun InventoryGUI<*>.changePage(effect: InventoryGUIPageChangeEffect, fr
 
         }
 
-        InventoryGUIPageChangeEffect.SLIDE_VERTICALLY -> {
+        PageChangeEffect.SLIDE_VERTICALLY -> {
 
             val height = data.inventoryType.dimensions.heigth
 
@@ -72,7 +82,7 @@ internal fun InventoryGUI<*>.changePage(effect: InventoryGUIPageChangeEffect, fr
 
         }
 
-        InventoryGUIPageChangeEffect.SWIPE_HORIZONTALLY -> {
+        PageChangeEffect.SWIPE_HORIZONTALLY -> {
 
             val width = data.inventoryType.dimensions.width
 
@@ -86,7 +96,7 @@ internal fun InventoryGUI<*>.changePage(effect: InventoryGUIPageChangeEffect, fr
 
         }
 
-        InventoryGUIPageChangeEffect.SWIPE_VERTICALLY -> {
+        PageChangeEffect.SWIPE_VERTICALLY -> {
 
             val height = data.inventoryType.dimensions.heigth
 
@@ -103,6 +113,12 @@ internal fun InventoryGUI<*>.changePage(effect: InventoryGUIPageChangeEffect, fr
     }
 }
 
+internal fun InventoryGUI<*>.changeGUI(
+    effect: InventoryChangeEffect,
+    fromPage: InventoryGUIPage<*>,
+    toPage: InventoryGUIPage<*>
+) = changePage(effect.effect, fromPage, toPage)
+
 private inline fun changePageEffect(
         kSpigot: KSpigot,
         fromPage: Int,