diff --git a/src/main/java/gregtech/api/metatileentity/multiblock/MultiMapMultiblockController.java b/src/main/java/gregtech/api/metatileentity/multiblock/MultiMapMultiblockController.java
index 493ef72b64f..74fe3e1e34d 100644
--- a/src/main/java/gregtech/api/metatileentity/multiblock/MultiMapMultiblockController.java
+++ b/src/main/java/gregtech/api/metatileentity/multiblock/MultiMapMultiblockController.java
@@ -136,7 +136,7 @@ public TraceabilityPredicate autoAbilities(boolean checkEnergyIn, boolean checkM
     protected MultiblockUIFactory createUIFactory() {
         IntSyncValue recipeMapValue = new IntSyncValue(this::getRecipeMapIndex, this::setRecipeMapIndex);
         return super.createUIFactory()
-                .createFlexButton((panel, syncManager, guiData) -> {
+                .createFlexButton((guiData, syncManager) -> {
                     if (getAvailableRecipeMaps() == null || getAvailableRecipeMaps().length <= 1)
                         return null;
 
diff --git a/src/main/java/gregtech/api/metatileentity/multiblock/ui/MultiblockUIFactory.java b/src/main/java/gregtech/api/metatileentity/multiblock/ui/MultiblockUIFactory.java
index 066eb4769a0..60cb6ed879b 100644
--- a/src/main/java/gregtech/api/metatileentity/multiblock/ui/MultiblockUIFactory.java
+++ b/src/main/java/gregtech/api/metatileentity/multiblock/ui/MultiblockUIFactory.java
@@ -14,7 +14,6 @@
 import gregtech.api.util.JsonUtils;
 import gregtech.api.util.KeyUtil;
 import gregtech.api.util.TextFormattingUtil;
-import gregtech.api.util.function.TriFunction;
 import gregtech.common.ConfigHolder;
 
 import net.minecraft.network.PacketBuffer;
@@ -47,18 +46,16 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.BiFunction;
 import java.util.function.Consumer;
-import java.util.function.Supplier;
 
 public class MultiblockUIFactory {
 
     private final MultiblockWithDisplayBase mte;
     protected Consumer<Builder> displayText, warningText, errorText;
-    protected TriFunction<ModularPanel, PanelSyncManager, PosGuiData, IWidget> flexButton = (panel, syncManager,
-                                                                                             posGuiData) -> null;
+    protected BiFunction<PosGuiData, PanelSyncManager, IWidget> flexButton = (guiData, syncManager) -> null;
     private int width = 198, height = 202;
     private int screenHeight = 109;
-    private Supplier<IWidget> customScreen;
     private Consumer<List<IWidget>> childrenConsumer;
 
     public MultiblockUIFactory(@NotNull MultiblockWithDisplayBase mte) {
@@ -197,7 +194,8 @@ public MultiblockUIFactory configureDisplayText(Consumer<Builder> displayText) {
      * <br>
      * Size will be 18x18.
      */
-    public MultiblockUIFactory createFlexButton(TriFunction<ModularPanel, PanelSyncManager, PosGuiData, IWidget> flexButton) {
+    public MultiblockUIFactory createFlexButton(
+                                                BiFunction<PosGuiData, PanelSyncManager, IWidget> flexButton) {
         this.flexButton = flexButton;
         return this;
     }
@@ -296,7 +294,7 @@ protected Widget<?> createScreen(PanelSyncManager syncManager) {
     @NotNull
     protected Flow createButtons(@NotNull ModularPanel mainPanel, @NotNull PanelSyncManager panelSyncManager,
                                  PosGuiData guiData) {
-        IWidget flexButton = this.flexButton.apply(mainPanel, panelSyncManager, guiData);
+        IWidget flexButton = this.flexButton.apply(guiData, panelSyncManager);
         if (flexButton == null) {
             flexButton = GTGuiTextures.BUTTON_NO_FLEX.asWidget()
                     .size(18)
diff --git a/src/main/java/gregtech/api/util/function/TriFunction.java b/src/main/java/gregtech/api/util/function/TriFunction.java
deleted file mode 100644
index 4b2cdda8258..00000000000
--- a/src/main/java/gregtech/api/util/function/TriFunction.java
+++ /dev/null
@@ -1,7 +0,0 @@
-package gregtech.api.util.function;
-
-@FunctionalInterface
-public interface TriFunction<T, U, Z, R> {
-
-    R apply(T t, U u, Z z);
-}
diff --git a/src/main/java/gregtech/common/metatileentities/multi/MetaTileEntityLargeBoiler.java b/src/main/java/gregtech/common/metatileentities/multi/MetaTileEntityLargeBoiler.java
index 283e9e9a4f8..ed73ae86345 100644
--- a/src/main/java/gregtech/common/metatileentities/multi/MetaTileEntityLargeBoiler.java
+++ b/src/main/java/gregtech/common/metatileentities/multi/MetaTileEntityLargeBoiler.java
@@ -197,7 +197,8 @@ protected void configureWarningText(MultiblockUIFactory.Builder builder) {
     @Override
     protected MultiblockUIFactory createUIFactory() {
         return super.createUIFactory()
-                .createFlexButton((panel, syncManager, guiData) -> {
+                .createFlexButton((guiData, syncManager) -> {
+                    // todo remove cast in next mui2 version
                     PanelSyncHandler throttle = (PanelSyncHandler) syncManager.panel("throttle_panel",
                             this::makeThrottlePanel, true);
 
@@ -206,7 +207,6 @@ protected MultiblockUIFactory createUIFactory() {
                             .overlay(GTGuiTextures.FILTER_SETTINGS_OVERLAY)
                             // todo lang
                             .addTooltipLine("Configure Boiler Throttle")
-                            // TODO make this work
                             .background(GTGuiTextures.BUTTON)
                             .onMousePressed(i -> {
                                 if (throttle.isPanelOpen()) {
@@ -214,6 +214,7 @@ protected MultiblockUIFactory createUIFactory() {
                                 } else {
                                     throttle.openPanel();
                                 }
+                                // todo remove this call in next mui2 version
                                 Interactable.playButtonClickSound();
                                 return true;
                             });