Using git

$ cd /some/convenient/dir
$ git clone https://github.com/obfusk/m-gui.git obfusk-m-gui
$ cd ~/bin                  # or some other dir on your $PATH
$ ln -s /some/convenient/dir/obfusk-m-gui/m-gui.py m-gui

Updating:

$ cd /some/convenient/dir/obfusk-m-gui
$ git pull

Using pip

$ pip3 install --user mmm-gui # for Debian; on other OS's you may need
                              # pip instead of pip3 and/or no --user

Building a Debian package

$ sudo apt install debhelper dh-python pandoc # install build dependencies
$ sudo apt install python3-gi libgtk-3-0 libvte-2.91-0  # run dependencies
$ cd /some/convenient/dir
$ git clone https://github.com/obfusk/m-gui.git obfusk-m-gui
$ cd obfusk-m-gui
$ dpkg-buildpackage
$ sudo dpkg -i ../mmm-gui_*_all.deb

Bookmarks

NB: since bookmarks are saved in gui.json, adding a bookmark from the GUI will open and re-save this file. Formatting is thus not preserved, data should be (unless you happen to trigger a race condition by writing to this file in between loading and saving by the GUI).

{
  "bookmarks": [
    "/some/media/dir",
    "/some/other/media/dir"
  ]
}

Defaults

{
  "scale": 2.0,
  "stay_fullscreen": true
}

Adding commands

{
  "add_commands": [
    [
      "mark-and-next space _Mark Playing and Play Next"
    ]
  ],
  "scripts": {
    "mark-and-next": "#{M} mark playing && #{M} next"
  }
}

m options

{
  "m_options": {
    "colour": true,
    "ignorecase": true,
    "numeric-sort": true,
    "show-hidden": true
  }
}

m command

{
  "m_command": "mmm"
}

NB: the command is passed to the shell, so you’ll need to escape/quote special characters (including spaces) appropriately; be careful!