IMO, it's not a great idea to stick more blocking dialogs in the normal flow for normal users. Given that there's already a setting to fix the issue this PR is for, it seems like a really niche use case for users who want that setting enabled and also don't (sometimes).
IMO, it would be better to just create two aliases (or shortcuts, bat(ch) scripts, etc) which run Geany in either mode, depending on the preference. I do this for example to use Geany as my Git editor with different command-line options/config directories from regular IDE use.
Then it becomes just running the appropriate command, like:
```bash $ geany-no-new foo.c bar.h # or $ geany-new foo.c bar.h ```