Upgrade snap core 18 to 22

- The current source code can no longer be built with core 18
- Bittorrent-tracker-editor must use GTK2
- The new newer Ubuntu snap system is now more focused on Gnome with GTK3.
- Some previous features no longer work for GTK2. Some improvisation is needed to get it working again.
- i386 is no longer supported in newer Ubuntu
- Can't get the theme to work anymore.

Need to spend more time to make it better

Author: GerryFerdinandus

snap/snapcraft.yaml

@@ -1,6 +1,6 @@
 name: bittorrent-tracker-editor
 version: '1.33.0'
-base: core18
+base: core22
 summary: Software for add or remove tracker from torrent files.
 description: |
   Features:
@@ -18,13 +18,12 @@ confinement: strict
 
 architectures:
   - build-on: amd64
-  - build-on: i386
   - build-on: arm64
   - build-on: armhf
 
 apps:
   bittorrent-tracker-editor:
-    command: desktop-launch $SNAP/app/trackereditor
+    command: app/trackereditor
     environment:
       # Fallback to XWayland if running in a Wayland session.
       DISABLE_WAYLAND: 1
@@ -51,59 +50,39 @@ parts:
     override-build: |
       snapcraftctl build
       lazbuild --build-mode=Release --widgetset=gtk2 source/project/tracker_editor/trackereditor.lpi
-      mkdir $SNAPCRAFT_PART_INSTALL/app
-      mv enduser/trackereditor $SNAPCRAFT_PART_INSTALL/app
-    stage-packages:
-      - libcanberra-gtk-module
-      - openssl
-      - libgail-common
-      - libatk-adaptor
-      - overlay-scrollbar-gtk2
-    after:
-      - desktop-gtk2
-
-  # This part installs the `desktop-launch` script which initialises desktop
-  # features such as fonts, themes and the XDG environment. It also installs
-  # the GTK2 runtime libraries.
-  #
-  # It is copied straight from the snapcraft desktop helpers project. Please
-  # periodically check the source for updates and copy the changes.
-  #    https://github.com/ubuntu/snapcraft-desktop-helpers/blob/master/snapcraft.yaml
-  #
-  desktop-gtk2:
-    source: https://github.com/ubuntu/snapcraft-desktop-helpers.git
-    source-subdir: gtk
-    plugin: make
-    make-parameters: ["FLAVOR=gtk2"]
+      mkdir $CRAFT_PART_INSTALL/app
+      mv enduser/trackereditor $CRAFT_PART_INSTALL/app
     build-packages:
       - libgtk2.0-dev
     stage-packages:
-      - libxkbcommon0  # XKB_CONFIG_ROOT
-      - ttf-ubuntu-font-family
-      - dmz-cursor-theme
-      - light-themes
-      - adwaita-icon-theme
-      - gnome-themes-standard
-      - shared-mime-info
       - libgtk2.0-0
-      - libgdk-pixbuf2.0-0
-      - libglib2.0-bin
-      - libgtk2.0-bin
-      - unity-gtk2-module
-      - libappindicator1
-      - locales-all
-      - ibus-gtk
-      - libibus-1.0-5
+      - openssl
+
+# This part removes all the files in this snap which already exist in
+# connected content and base snaps. Since these files will be available
+# at runtime from the content and base snaps, they do not need to be
+# included in this snap itself.
+#
+# More info: https://forum.snapcraft.io/t/reducing-the-size-of-desktop-snaps/17280#heading--cleanup-part
+#
+  cleanup:
+    after:  # Make this part run last; list all your other parts here
+      - bittorrent-tracker-editor
+    plugin: nil
+    build-snaps:  # List all content-snaps and base snaps you're using here
+      - core22
+      - gtk-common-themes
+    override-prime: |
+      set -eux
+      for snap in "core22" "gtk-common-themes"; do  # List all content-snaps and base snaps you're using here
+          cd "/snap/$snap/current" && find . -type f,l -exec rm -f "$SNAPCRAFT_PRIME/{}" \;
+      done
 
 plugs:
   gtk-2-engines:
     interface: content
     target: $SNAP/lib/gtk-2.0
     default-provider: gtk2-common-themes
-  gtk-2-themes:
-    interface: content
-    target: $SNAP/data-dir/themes
-    default-provider: gtk-common-themes
   icon-themes:
     interface: content
     target: $SNAP/data-dir/icons