Looks like I wrote a similar program

[porky11]

I just found this when searching for a similar program I wrote myself.
I was looking for some petri net simulation software for some time before I started writing my own.
Your program is a good inspiration for what's still missing in my one, but I think, my program also has a bunch of benefits.

I like the UI of your program. Besides of the petri net itself I don't have much UI in my program. It's something, that should probably be added to my program, too.
Also your program has some other features, that might be useful. Especially subnets and the boundness check.
But I don't get how subnets work in your program.
Also I wonder what actors are used for.

Here the benefits of my program, which might be interesting for this program as well:

• user friendly shortcuts for everything
• more user friendly controls in general (probably just an opinion)
• reverting fire transitions (unfire)
• multiple simulation states, you can switch between
• mark fireable (and unfireable) transitions
• based on a C API, which is used for simulation, editing, saving, loading
  • other programs (for example an interactive story program or a game engine) can also use the generated net using the same API
  • API can be used by almost every langauge
• simple data formats for saving and loading, so you could easily parse them yourself
• ablility to store text data to transitions (more than labels)

Maybe you're interested in looking at it and get inspiration for your program as well (or want to implement missing features into my program yourself :P)