That depends a lot on how the program interacts with the open file. It doesn’t really have anything to do with Dropbox. Dropbox is just acting as a mirror. If you hold up a frightening picture in front of the mirror, you can’t really blame the mirror for producing a scary image. So if the program holds the file open in a state where another program cannot open the file correctly, that’s just how things have got to be with that particular program, and no synchronisation software sitting on top of the disk is ever going to change that.
The situation is roughly similar for Scrivener because the whole project is decidedly different while open, than closed. Dropbox is just being a good mirror here and showing the second user what the open project looks like on the disk.
P.S. There is no need to post the same exact message on multiple boards. We watch them all, so it only adds clutter and increases the chance of getting split discussions where one discussion would be better for everyone.
No worries! I already took care of it. There are a few tools on the forum that we use to help us see across many sections at once. The link that lets you view new posts shows you everything you’ve not read yet no matter where it is posted. So we’ll see it wherever it goes.