Sets the environment variable variable in the environment of processes launched from this launcher.
Both the variable's name and value should be in the GLib file name encoding. On UNIX, this means that they can be arbitrary byte strings. On Windows, they should be in UTF-8.
| this | |
| variable |
the environment variable to set, must not contain '=' |
| value |
the new value for the variable |
| overwrite |
whether to change the variable if it already exists |