AppImage is a software package that can be installed and run on various Linux
distros.  It has several advantages in that there is no need to install or
compile software and no need to have root permission.  In addition, no system
files are modified and you can simply delete the software by deleting the 
AppImage file.

To install an AppImage, download it, make it executable and run it. It is a 
compressed image and contains all the dependencies/libraries needed to run.

  1) download AppImage file  move from Download folder to your preference
  2) make it executable         chmod u+x {AppImageFile name}
  3) run it, for example ./CinGG-date-x86_64.AppImpage

ARCH requires install of the "libappimage" package.
LEAP 15.3 (openSUSE) requires install of the "appimage" package.
If using the OpenGL video driver, you must install OpenGL drivers on your O/S.

*****  Alternative GUI method to download provided by Leap 15.3 user *****
To run and integrate Cinelerra AppImage with installed "AppImageLauncher",
follow the next few steps.  On at least some distros, AppImageLauncher is 
integrated with Firefox.  Build packages for AppImageLauncher (rpm, deb)
to install are found here:

     https://github.com/TheAssassin/AppImageLauncher/releases/tag/continuous

   1) Start to download the AppImage file, and a widget popups in Firefox
      with the option to open it with AppImageLauncher (instead of saving).
   2) At the end of the download a new popup asks to integrate it with
      your desktop system, so click OK.  The AppImage installation directory
      is /home/user/Application by default, but can be changed.

This automatically is integrated with icons and in the Gnome app-menu,