Flatpak

Flatpak is Article description::a package management framework aiming to provide support for sandboxed, distro-agnostic binary packages for Linux desktop applications.

Files

 * - global flatpak state (system-wide installed apps and repos)
 * - per-user flatpak state (locally installed apps and repos)
 * - per application state (configuration files and cache)

Basic usage
To install an application, e.g. Thunderbird, run:

To run the application use created .desktop file or run:

To update installed applications and runtimes:

Theming
Flatpak documentiation offers a good guide about desktop integration and theming.

GTK
Flatpak applications don't follow the system's GTK theme by default. First find out what's the current GTK theme, e.g. Materia-dark-compact, and then install it for Flatpak applications to use.

Desktop integration for Wayland
When using WMs such as Sway, installing xdg portals is needed for full integration. There are different backends available for this matter:


 * GTK backend: 'xdg-desktop-portal-gtk'
 * KDE backend 'xdg-desktop-portal-kde' (in development)
 * Wayland/wlroots backend: 'xdg-desktop-portal-wlr' (in development)

Ensuring portals are running
Please note that sometimes these libraries aren't pulled automatically by the OS and need to be run by the user, for example they can be pulled in Sway configuration:

Fixing jagged fonts on Wayland
Some users report jagged fonts on Wayland. The workaround is to install gnome-settings-daemon.

Caveats
There are different views on the security of Flatpak. The infamous "Flatkill" essay covers several reported problems, although some have noted it lacks some nuance and have responded here. Make up your own mind.