Added GuiOpenEvent

You can use this for a clean way to override guis, without needing an
TickHandler to check if the gui you want to override is open and show
your own gui

Proper close check

client/net/minecraftforge/client/event/GuiOpenEvent.java

@@ -0,0 +1,22 @@
+package net.minecraftforge.client.event;
+
+import net.minecraft.client.gui.GuiScreen;
+import net.minecraftforge.event.Cancelable;
+import net.minecraftforge.event.Event;
+
+/**
+ * This event is called before any Gui will open.
+ * If you don't want this to happen, cancel the event.
+ * If you want to override this Gui, simply set the gui variable to your own Gui.
+ * 
+ * @author jk-5
+ */
+@Cancelable
+public class GuiOpenEvent extends Event
+{
+    public GuiScreen gui;
+    public GuiOpenEvent(GuiScreen gui)
+    {
+        this.gui = gui;
+    }
+}

patches/minecraft/net/minecraft/client/Minecraft.java.patch

@@ -1,11 +1,12 @@
 --- ../src_base/minecraft/net/minecraft/client/Minecraft.java
 +++ ../src_work/minecraft/net/minecraft/client/Minecraft.java
-@@ -137,6 +137,14 @@
+@@ -137,6 +137,15 @@
  
  import com.google.common.collect.MapDifference;
  
 +import net.minecraftforge.client.ForgeHooksClient;
 +import net.minecraftforge.client.GuiIngameForge;
++import net.minecraftforge.client.event.GuiOpenEvent;
 +import net.minecraftforge.common.ForgeHooks;
 +import net.minecraftforge.common.MinecraftForge;
 +import net.minecraftforge.event.ForgeEventFactory;
@@ -15,7 +16,7 @@
  @SideOnly(Side.CLIENT)
  public class Minecraft implements IPlayerUsage
  {
-@@ -416,7 +424,7 @@
+@@ -416,7 +425,7 @@
  
          try
          {
@@ -24,7 +25,7 @@
          }
          catch (LWJGLException lwjglexception)
          {
-@@ -497,7 +505,7 @@
+@@ -497,7 +506,7 @@
          this.effectRenderer = new EffectRenderer(this.theWorld, this.renderEngine);
          FMLClientHandler.instance().finishMinecraftLoading();
          this.checkGLError("Post startup");
@@ -33,7 +34,49 @@
  
          if (this.serverName != null)
          {
-@@ -1300,7 +1308,7 @@
+@@ -679,20 +688,30 @@
+      */
+     public void displayGuiScreen(GuiScreen par1GuiScreen)
+     {
++        this.statFileWriter.syncStats();
++
++        if (par1GuiScreen == null && this.theWorld == null)
++        {
++            par1GuiScreen = new GuiMainMenu();
++        }
++        else if (par1GuiScreen == null && this.thePlayer.func_110143_aJ() <= 0.0F)
++        {
++            par1GuiScreen = new GuiGameOver();
++        }
++        
++        GuiScreen old = this.currentScreen;
++        GuiOpenEvent event = new GuiOpenEvent(par1GuiScreen);
++        boolean canceled = MinecraftForge.EVENT_BUS.post(event);
++        if(old != null && old != this.currentScreen)
++        {
++            old.onGuiClosed();
++        }
++        if(canceled) return;
++        par1GuiScreen = event.gui;
++        
+         if (this.currentScreen != null)
+         {
+             this.currentScreen.onGuiClosed();
+-        }
+-
+-        this.statFileWriter.syncStats();
+-
+-        if (par1GuiScreen == null && this.theWorld == null)
+-        {
+-            par1GuiScreen = new GuiMainMenu();
+-        }
+-        else if (par1GuiScreen == null && this.thePlayer.func_110143_aJ() <= 0.0F)
+-        {
+-            par1GuiScreen = new GuiGameOver();
+         }
+ 
+         if (par1GuiScreen instanceof GuiMainMenu)
+@@ -1300,7 +1319,7 @@
  
                  if (this.thePlayer.isCurrentToolAdventureModeExempt(j, k, l))
                  {
@@ -42,7 +85,7 @@
                      this.thePlayer.swingItem();
                  }
              }
-@@ -1366,7 +1374,8 @@
+@@ -1366,7 +1385,8 @@
                  {
                      int j1 = itemstack != null ? itemstack.stackSize : 0;
  
@@ -52,7 +95,7 @@
                      {
                          flag = false;
                          this.thePlayer.swingItem();
-@@ -1392,7 +1401,8 @@
+@@ -1392,7 +1412,8 @@
              {
                  ItemStack itemstack1 = this.thePlayer.inventory.getCurrentItem();
  
@@ -62,7 +105,7 @@
                  {
                      this.entityRenderer.itemRenderer.resetEquippedProgress2();
                  }
-@@ -2046,6 +2056,11 @@
+@@ -2046,6 +2067,11 @@
      {
          this.statFileWriter.syncStats();
  
@@ -74,7 +117,7 @@
          if (par1WorldClient == null)
          {
              NetClientHandler netclienthandler = this.getNetHandler();
-@@ -2063,6 +2078,18 @@
+@@ -2063,6 +2089,18 @@
              if (this.theIntegratedServer != null)
              {
                  this.theIntegratedServer.initiateShutdown();
@@ -93,7 +136,7 @@
              }
  
              this.theIntegratedServer = null;
-@@ -2236,107 +2263,12 @@
+@@ -2236,107 +2274,12 @@
          if (this.objectMouseOver != null)
          {
              boolean flag = this.thePlayer.capabilities.isCreativeMode;
@@ -205,7 +248,7 @@
  
              if (flag)
              {
-@@ -2419,11 +2351,18 @@
+@@ -2419,11 +2362,18 @@
          par1PlayerUsageSnooper.addData("gl_max_texture_size", Integer.valueOf(getGLMaximumTextureSize()));
      }
  
@@ -224,7 +267,7 @@
          for (int i = 16384; i > 0; i >>= 1)
          {
              GL11.glTexImage2D(GL11.GL_PROXY_TEXTURE_2D, 0, GL11.GL_RGBA, i, i, 0, GL11.GL_RGBA, GL11.GL_UNSIGNED_BYTE, (ByteBuffer)null);
-@@ -2431,6 +2370,7 @@
+@@ -2431,6 +2381,7 @@
  
              if (j != 0)
              {