I'm trying to replace a preexisting dispenser behavior with my own, but just registering a new behavior in post init doesn't seem to override the vanilla one. Everything I've read seems to indicate that there is a way to remove behaviors, but no one ever mentions what it is. 

That's what I tried, but the dispenser still behaves as normal.

 

Specifically, I'm trying to replace the behavior of placing skulls, so that it can't be used to automatically make withers. In post init, did this:

public static void postInit(FMLPostInitializationEvent event)
    {
    	BlockDispenser.DISPENSE_BEHAVIOR_REGISTRY.putObject(Items.SKULL, new BehaviorDefaultDispenseItem());
    	
	}

I assumed this would make it just spit the skull out, but it seems i was mistaken. Did I do something wrong here, or was my assumption incorrect?

I'm pretty sure it is, ill add a debug out to check

 

You were right, its not being called at all. And I think I know why, I forgot the event handler annotation.

That did the trick! Thanks a lot! 

For anyone who has this problem in the future, here's my final code:

@EventHandler
    public static void postInit(FMLPostInitializationEvent event)
    {
    	BlockDispenser.DISPENSE_BEHAVIOR_REGISTRY.putObject(Items.SKULL, new BehaviorDefaultDispenseItem());
    	System.out.println("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!");
	}

The println is just so i see it in the log.