Looking good, working even better.
Many thanks for adding the ability to load different chest files.
One minor detail that could (but doesn't have to ) be polished is that after one decodes a chest a file, he has to encode it back (and for the button to enable you have to click save item button) to be able to open another chest. So even if one hasn't made any changes to a chest, he has to save and encode to be able to work with another file. Not a very disturbing feature, but maybe you could leave a little bit of room for user to act.
The same applies to changing multiple items in chest. If one changes an item and clicks another one, the encode button disables until another save item action.
I don't mean to be choosy, cause after all it's your project. Besides I can probably guess why you made it this way (minimalize the chance of users corrupting saves or crashing application, wasn't it? ). So if you change it or leave it as is is totally up to you.
Other than that the program is pure awesome.
One question - can you tell me which byte (counting from the beginning of the byte array defining an item) is the "index of item in chest"? And I wonder if you tried changing this index for something else - would it corrupt the chest? If for example there are two different items with the same index. I know it's not possible to change the index with your program, so I'm only asking hypothetically.
PS. Thanks for the lightsabers tip. This time (using your editor and with normal yellow saber, not a unique) it worked. Lookee here: Link
. Kinda more like Star Wars than Sacred, don't you think?