This mod allows modpacks to provide different launch-level configuration options that users can select between either on first launch or by pressing the Config button of the Launch Configuration mod (changes made this way only come into effect after a restart).

This mod's configuration file is located at config/launchconfiguration_settings.json. An example settings file that corresponds to the picture above:

{
  "description": "This modpack provides a few launch configuration options",
  "options": [
    {
      "name": "Recipe viewer mod",
      "description": "Choose the recipe viewer mod to use in this modpack",
      "values": [
        {
          "name": "JEI",
          "description": "JustEnoughItems is a mod by mezz",
          "behaviours": [
            {
              "type": "disable_mod",
              "modId": "emi"
            }
          ]
        },
        {
          "name": "EMI",
          "description": "EMI is a mod by EmilyPloszaj",
          "behaviours": [
            {
              "type": "disable_mod",
              "modId": "jei"
            }
          ],
          "fallback": true
        }
      ]
    }
  ]
}

Behaviour supported currently:

disabling a mod (e.g. choosing between JEI and EMI, or TOP and Jade) - type disable_mod, with modId being the ID of the mod to disable
copying files (e.g. choosing between 2 template configs) - type copy_file, with from being the source path of the file (relative to game dir root) and to being the target destination to copy to (relative to game dir root)

Note: the UI uses Swing, the built-in UI library in Java. To avoid issues with Mac users, the GUI is spawned in a different child process.