Defines the GBC component to be used in GUI direct mode.

The FGLGBCDIR environment variable can be used to define the directory where the GBC component must be loaded from.

The FGLGBCDIR environment variable is provided to select a given GBC when using the GUI direct mode. FGLGBCDIR is ignored when using the GAS: As a general pattern, if a specific GBC is to be coupled with a particular application in production, consider shipping GBC in appdir/gbc. Otherwise, use the GBC available by default.

The GBC component will be searched in the following directories:
  1. The appdir/gbc directory, where appdir is the directory where the program file is located,
  2. The directory defined in the FGLGBCDIR environment variable,
  3. The $FGLDIR/web_utilities/gbc/gbc directory.

If defined, make sure that FGLGBCDIR is set to a directory containing the GBC component files.