Tasman, you bring up a good point...
A couple of days ago, I looked at the language folder on my server and thought of that too. It might be useful to have a graphical tool for editing skills, maps, and monster sets. For me I edit shop files and warehouse frequently, as I do some internal server testing. As this program alone required a lot of work already, extending support to other features of the server is unlikely at this point.
Updates on the program:
Title: Mu Item Bag/Shop Editor
1) Only opens shop and event item bag files (file names must include have "shop" or "bag")
There is no easy way to FULLY detect if a file is valid for reading, so I just implemented this simple check. You can easily fool it, but just don't.
2) The "Tab-delimited Output" is now eliminated. It was used for formatting eventitembag8.txt - eventitembag12.txt. Now, the program will automatically check if the item bag file contains any excellent items, than output it in tab-delimited format, so the server won't crash when reading the file.
3) Blank lines and comments are now supported. They are also preserved during file open.
4) Recently added support for "sub-type" items (Box of Kundun, Transformation Rings, Orbs,etc)
5) There are some properties that I will not check. For example, if you make a satan+skill, that's your choice. It's too much work for me to check it, and the game engine will check it anyway. I leave this possibility to you, as there might be "uses" for it.
Future udpates:
1) Filter for excellent options
Request to the ragezone community:
Wing options (both normal and excellent) seem to be a mystery to me and some of you. If anyone can post information about this, it would be great. This will be useful in future extension to support editing the warehouse.