Add Loadable, called when a GUI should load things

src/main/java/de/johni0702/minecraft/gui/container/AbstractGuiOverlay.java

@@ -62,6 +62,7 @@ public abstract class AbstractGuiOverlay<T extends AbstractGuiOverlay<T>> extend
     public void setVisible(boolean visible) {
         if (this.visible != visible) {
             if (visible) {
+                forEach(Loadable.class).load();
                 MinecraftForge.EVENT_BUS.register(eventHandler);
             } else {
                 forEach(Closeable.class).close();

src/main/java/de/johni0702/minecraft/gui/container/AbstractGuiScreen.java

@@ -221,6 +221,7 @@ public abstract class AbstractGuiScreen<T extends AbstractGuiScreen<T>> extends
             }
             screenSize = new Dimension(width, height);
             renderer = new MinecraftGuiRenderer(new ScaledResolution(mc, mc.displayWidth, mc.displayHeight));
+            forEach(Loadable.class).load();
         }
 
         public T getWrapper() {

src/main/java/de/johni0702/minecraft/gui/function/Loadable.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) 2015 johni0702
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+package de.johni0702.minecraft.gui.function;
+
+public interface Loadable {
+    void load();
+}