Hi Skye,
I did look into this a little further, and I was actually given some good suggestions on how you could make your own type of lock. I haven't had the chance to attempt this myself yet, but figured I would at least give you some ideas while I am working on this. There are a couple different approaches you could take, to start, you could add a "Lock Button" to the screen being worked on. So, for your case, your user would open the screen where they create the ticket, once opened they would press the lock button. The lock button would have actions to "hide" certain sections, or "save" button so that only the person working on the screen currently would be able to manipulate it until they have pressed either the Lock Button again, or an "Unlock Button".
You could also likely do something with the OnScreenLoad action, similar to the button, to hide sections/buttons from anyone else how tries to open the same ticket, if it has already been opened. If this is a pop-up screen, you could then add an action once PopUpClosed to unlock the ticket again.
As I said, I haven't had a chance to work on this yet, I know our in-house consulting team has been able to use both these types of approaches in the past. I plan on doing a little testing on this later today or tomorrow morning, and if I can give you any more specifics at this point, I will. Please let me know if this has helped you figure out a solution in the mean time.
-Ben