Where to find application after flatpak installation (gimp)

I have installed flatpak to install gimp on Ubuntu 16.04:

flatpak install https://flathub.org/repo/appstream/org.gimp.GIMP.flatpakref

After the installation was done I couldn't find any application on my system, it also did not appear on my Desktop. Where to look for it?

UPDATE: Searching for gimp did not give me the right result, anyway by searching for GNU Image Manipulation Program gave me the right result

To run Gimp:

flatpak run org.gimp.GIMP "$@"

But AFAIK there is a desktop file somewhere, I have a ~/.local/share/applications/org.gimp.GIMP.desktop with:

[Desktop Entry]
Categories=Graphics;2DGraphics;RasterGraphics;GTK;
Comment=Create images and edit photographs
Exec=/usr/bin/flatpak run --branch=stable --arch=x86_64 --command=gimp-2.10 --file-forwarding org.gimp.GIMP @@u %U @@
GenericName=Image Editor
Icon=org.gimp.GIMP
Keywords=GIMP;graphic;design;illustration;painting;
MimeType=image/bmp;image/g3fax;image/gif;image/x-fits;image/x-pcx;image/x-portable-anymap;image/x-portable-bitmap;image/x-portable-graymap;image/x-portable-pixmap;image/x-psd;image/x-sgi;image/x-tga;image/x-xbitmap;image/x-xwindowdump;image/x-xcf;image/x-compressed-xcf;image/x-gimp-gbr;image/x-gimp-pat;image/x-gimp-gih;image/tiff;image/jpeg;image/x-psp;application/postscript;image/png;image/x-icon;image/x-xpixmap;image/x-exr;image/x-webp;image/heif;image/heic;image/svg+xml;application/pdf;image/x-wmf;image/jp2;image/x-xcursor;
Name=Gimp 2.10
NoDisplay=false
Path[$e]=
StartupNotify=true
Terminal=0
TerminalOptions=
Type=Application
Version=1.0
X-Flatpak=org.gimp.GIMP
X-Flatpak-Tags=stable;
X-GNOME-Bugzilla-Bugzilla=GNOME
X-GNOME-Bugzilla-Component=General
X-GNOME-Bugzilla-OtherBinaries=gimp-2.10
X-GNOME-Bugzilla-Product=GIMP
X-GNOME-Bugzilla-Version=2.10.2
X-KDE-SubstituteUID=false
X-KDE-Username=

The real installation is in /var/lib/flatpak/app/org.gimp.GIMP/

If you are used to "native" Gimp, be aware of some restrictions:

• the "recent files" are not shared with other apps in the system
• the /tmp directory as seen by Gimp is remapped to a directory specific to flatpak, so you cannot share files through that (which is unfortunately required for some apps, such as web browsers)
• the Python runtime is specific to Gimp
• the Gimp profile is buried in ~/.var/app/org.gimp.GIMP/config/GIMP/2.10/
• you may want to use Edit>Preferences>Folders to setup folders in more "visible" directories for your brushes, patterns, scripts and plugins
• compatibility with the popular plugins (GMIC, resynthesize...) isn't clear. It seems this requires flatpak versions.

In short: Reboot or log out and log in after installing the flatpak package to see flatpak apps in the launcher.

Explanation:

Flatpak collects all .desktop files of system-wide installed applications in /var/lib/flatpak/exports/share/applications and of per-user applications in ~/.local/share/flatpak/exports/share/applications.^[1]

Application launchers search for apps in $XDG_DATA_HOME directory (default ~/.local/share) and $XDG_DATA_DIRS colon-separated list (default /usr/local/share/:/usr/share/).^[2][3]

flatpak Ubuntu package installs /etc/profile.d/flatpak.sh script that adds the aforementioned flatpak export directories to XDG_DATA_DIRS on startup. And just running the script after install won't help, it has to be done before the desktop starts because it reads that environment variable only when starting.