[Unanswered] [1.5_01] Giving a block a GUI help?

So I'm trying to give a block the GUI of a dispenser. I really have no idea how to do it, but I whipped up some code real quick.
I can craft the block and everything, but when I try to open/right-click

mod_MagicBox

Code:

package net.minecraft.src;

public class mod_MagicBox extends BaseMod
{

   public static final Block MagicBox = new BlockMagicBox(200, 0).setHardness(1.5F).setResistance(1.0F).setBlockName("MagicBox");
   
   public mod_MagicBox()
   {
   ModLoader.RegisterBlock(MagicBox);
   
     ModLoader.AddName(MagicBox, "Magic Box");
    
     ModLoader.AddRecipe(new ItemStack(MagicBox, 1), new Object[] {
          "XXX", "XZX", "XXX", Character.valueOf('X'), Block.cobblestone, Character.valueOf('Z'), Item.redstone
  });
   }

BlockMagicBox

Code:

package net.minecraft.src;

public class BlockMagicBox extends Block
{

    protected BlockMagicBox(int i, int j)
    {
        super(i, j, Material.rock);
    }




public boolean blockActivated(World world, int i, int j, int k, EntityPlayer entityplayer)
{
    if(world.multiplayerWorld)
    {
        return true;
    } else
    {
        TileEntityDispenser tileentitydispenser = (TileEntityDispenser)world.getBlockTileEntity(i, j, k);
        entityplayer.displayGUIDispenser(tileentitydispenser);
        return true;
    }
}}

EDIT: HERE'S THE ERROR MESSAGE FROM ECLIPSE

Code:

16 achievements
146 recipes
ModLoader Beta 1.5_01 Initializing...
Mod Loaded: net.minecraft.src.mod_MagicBox 1.4_01
Done.
WARNING: Found unknown Windows version: Windows 7
Attempting to use default windows plug-in.
Loading: net.java.games.input.DirectAndRawInputEnvironmentPlugin
Failed to initialize device 2.4GHz Cordless Desktop because of: java.io.IOException: Failed to acquire device (8007001e)

Starting up SoundSystem...
Initializing LWJGL OpenAL
    (The LWJGL binding of OpenAL.  For more information, see http://www.lwjgl.org)
OpenAL initialized.

java.lang.NullPointerException
   at net.minecraft.src.ContainerDispenser.isUsableByPlayer(ContainerDispenser.java:40)
   at net.minecraft.src.EntityPlayer.onUpdate(EntityPlayer.java:66)
   at net.minecraft.src.World.updateEntityWithOptionalForce(World.java:1350)
   at net.minecraft.src.World.updateEntity(World.java:1326)
   at net.minecraft.src.World.func_633_c(World.java:1300)
   at net.minecraft.client.Minecraft.runTick(Minecraft.java:1125)
   at net.minecraft.client.Minecraft.run(Minecraft.java:451)
   at java.lang.Thread.run(Unknown Source)
Stopping!

SoundSystem shutting down...

The last part I copied and pasted from BlockDispenser.
I don't think is is correct at all, but help would be appreciated

what happens when you open/right click?
I had a fast check through TileEntityDispenser.java and well, you know, it has many more functions, like taking a random item out of 9 item slots and read, write something to NBT something(which i dont understand) and those functions i think wont work if you dont have something particular(sorry i dont know either )
Can any1 give a good solution and
btw, how to make your own GUI like the craft table which you can have the output slot and user-defined input slots

It only crashes when I right click on the block.

try this

Code:

package net.minecraft.src;

public class BlockMagicBox extends Block
{

    protected BlockMagicBox(int i, int j)
    {
        super(i, j, Material.rock);
    }




public boolean blockActivated(World world, int i, int j, int k, EntityPlayer entityplayer)
{
    if(world.multiplayerWorld)
    {
        return true;
    } else
    {
        entityplayer.displayGUIDispenser(tileentitydispenser);
        return true;
    }
}}

I deleted this part

Code:

TileEntityDispenser tileentitydispenser = (TileEntityDispenser)world.getBlockTileEntity(i, j, k);

I get an error on

(tileentitydispenser);

Maybe if you tried chest?

just so you know guis are complicated

ah i tried to make new blocks show dispenser gui but they just dont work, still wonder why

Add this:

Code:

protected TileEntity getBlockEntity()
    {
        return new TileEntityFurnace();
    }