Initial port to 1.18

Co-authored-by: David Quintana <gigaherz@gmail.com>
Co-authored-by: SizableShrimp <sizableshrimp@sizableshrimp.me>

src/main/java/net/minecraftforge/client/ConfigGuiHandler.java

@@ -0,0 +1,39 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016-2021.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+package net.minecraftforge.client;
+
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.gui.screens.Screen;
+import net.minecraftforge.fml.ModList;
+import net.minecraftforge.fml.IExtensionPoint;
+import net.minecraftforge.forgespi.language.IModInfo;
+
+import java.util.Optional;
+import java.util.function.BiFunction;
+
+public class ConfigGuiHandler
+{
+    public record ConfigGuiFactory(BiFunction<Minecraft, Screen, Screen> screenFunction) implements IExtensionPoint<ConfigGuiFactory> {}
+    public static Optional<BiFunction<Minecraft, Screen, Screen>> getGuiFactoryFor(IModInfo selectedMod)
+    {
+        return ModList.get().getModContainerById(selectedMod.getModId()).
+                flatMap(mc -> mc.getCustomExtension(ConfigGuiFactory.class).map(ConfigGuiFactory::screenFunction));
+    }
+}