Yes, I finally installed it via Flatpak. What a fun adventure! First, I had to install Flatpak with apt. Then, I downloaded the Foliate .flatpakref. I installed it with `flatpack install com.github.johnfactotum.Foliate.flatpakref`, which worked the first time!
No, it didn't. Of course, Flatpak let me know that my user account didn't have the ability to configure the remote repositories the Foliate flatpakref specified. I could have searched for the right way to do it, but installing as root seemed to work, and it runs fine as a regular user, too!
But, of course, it doesn't. It doesn't have the ability to open files from most folders. I see by searching that you set sandbox permissions in an application manifest file, but I'm not sure I'm that attached to doing any more of this.
Installing it via "flatpak install foliate" didn't work? Downloading the .flatpakref seems like an unnecessary step to me but I'm on a different distro (openSUSE Tumbleweed).
edit: I can also open files from anywhere on my PC. Could it be that the flatpak on Debian Stretch is not correctly configured?
I'm pretty sure your edit nails it: flatpak on my moldy Debian doesn't work correctly as a non-root user, and the alternative of running it as root and then running the application as a normal user was neither intended nor foreseen.
I did finally install Debian testing, and it looks like the flatpak problems are resolved, but I decided not to bother installing foliate because of the nearly 700MB of dependencies it wanted over my rural satellite connection. C'est la vie.
I went ahead and burned the data: for Science! After the dependencies were all downloaded, it works correctly and completely. It's a fairly nice ebook reader application, and it only took three days and replacing my operating system to get it.
You can build your own Flatpaks from source, too. In fact that's probably how a lot of development is done these days around GNOME and its wider community when using Gnome Builder. You make a change, and Gnome Builder builds a Flatpak and runs it for you so you can test it.
No, it didn't. Of course, Flatpak let me know that my user account didn't have the ability to configure the remote repositories the Foliate flatpakref specified. I could have searched for the right way to do it, but installing as root seemed to work, and it runs fine as a regular user, too!
But, of course, it doesn't. It doesn't have the ability to open files from most folders. I see by searching that you set sandbox permissions in an application manifest file, but I'm not sure I'm that attached to doing any more of this.