After upgrading from GanttProject 2.8.10 to 2.9.11, my system doesn’t recognize the file dependency of the .gan files to the application any more – in my case it is taken to be a BBEdit document (see »FinderInfoForA-gan-file.png«).
I even couldn’t redefine it in Finder, because GanttProject.app is not correctly recognized as an application (see »FinderRedefiningFails.png«).
It worked fine in my tests.
What is on the second screenshot? It does not look like our official distro for macOS (there is no logo.png in our distro, and the license file is just LICENSE), it does not look like Applications folder. Normally, in macOS you don’t see .app extension in Finder. Are you sure that GanttProject.app in this folder is an application indeed?
I am not sure that it is only your machine issue. There are so many macOS versions around and they are so different. What macOS are you running? Also, did you try moving GanttProject into Applications?
Thank you for your investigation. Meanwhile I managed to associate .gan to GanttProject, but the file icon remains BBEdit’s one. I can live with that and maybe the upgrade, I’ll plan do, will fix this either.
I’ll leave you a message here, if it worked.
Tobias