Should be able to edit things after you add them and delete one thing at a time

Now, here is a re-ocurring way that MCreator works which has been bugging (no pun intended) me and probably lots of other people for a long time.

Look at events, adding mobs to biomes, adding ai tasks to mobs, and schematics to custom dimensions - you cant edit them once you press "add". I found schematics in custom dimensions was quite enfuriating because if you made one spawn too commonly you'd have to clear the ENTIRE list just to re-do it. 

So, 2 things in one really:
- Make it so you can edit these things after you have added them, or more importantly
- Make it so you don't have to clear EVERYTHING but can delete different components individually

Thanks, this would honestly make all of our lives so much better!