GuiEvents

public class GuiEvents {

    @SubscribeEvent
    public void overdrawGui(GuiScreenEvent.InitGuiEvent e){
        GuiScreen screen=null;
        if(e.getGui() instanceof GuiWorldSelection)
            Minecraft.getMinecraft().displayGuiScreen(new net.rexozz.pixelengine.client.gui.GuiWorldSelection(screen));
        else
            screen=e.getGui();
    }

    public static void tryLoadExistingWorld(net.rexozz.pixelengine.client.gui.GuiWorldSelection selectWorldGUI, WorldSummary comparator)
    {
        File dir = new File(new File(Minecraft.getMinecraft().mcDataDir, "saves"), comparator.getFileName());
        NBTTagCompound leveldat;
        try
        {
            leveldat = CompressedStreamTools.readCompressed(new FileInputStream(new File(dir, "level.dat")));
        }
        catch (Exception e)
        {
            try
            {
                leveldat = CompressedStreamTools.readCompressed(new FileInputStream(new File(dir, "level.dat_old")));
            }
            catch (Exception e1)
            {
                FMLLog.warning("There appears to be a problem loading the save %s, both level files are unreadable.", comparator.getFileName());
                return;
            }
        }
        NBTTagCompound fmlData = leveldat.getCompoundTag("FML");
        if (fmlData.hasKey("ModItemData"))
        {
            GuiScreen gui = (GuiScreen) new GuiOldSaveLoadConfirm(comparator.getFileName(), comparator.getDisplayName(), selectWorldGUI);
            Minecraft.getMinecraft().displayGuiScreen(gui);
        }
        else
        {
            try
            {
                Minecraft.getMinecraft().launchIntegratedServer(comparator.getFileName(), comparator.getDisplayName(), null);
            }
            catch (StartupQuery.AbortedException e)
            {
                // ignore
            }
        }
    }

}