Reset untitled counter when creating a new form

[lognaturel]

Create a new form, add a few controls which will be numbered untitled1, untitled2, etc. Open a new form and the numbering will continue where it left off rather than restarting.

This isn't a big deal but it's a little bit surprising. Maybe it'd make for a good quick win for a new contributor?

[issa-tseng]

Yeah, I know of this behaviour. It's not quick or I'd have fixed it.