It’s maybe simple… but it might be an improvement to be able to lock applications when you are done. especially when you work with more people on one project. But also for your self … the handling of first unlocking before you can edit works like a reminder that you already had finished that one…
and it also prevents you from deleting applications that were not mend to be deleted.
… just a thought 
Re: Locking applications
Its nice, but we have an option to increase the project version.
Thats mean, if you finish a project or part of it or a module or a application … you can increase the project version and lock the current version. This give you the power to work on the new version without change the current one. And you have the possibility to re-open the old project, restore one application …
but its a good sugestion.
Re: Locking applications
Yes i have seen the project versions option… but i was thinking on application level.
i got this idea when i had a lot of applications in a project… a lot of them were for test purpose only… and when i removed them i was a bit to enthusiastic and removed 2 applications to many…