GUI log events

The GUI protocol supports a special front-end event named "LogEvent", to add a marker in the GUI log, with some debug data.

When a log event is fired, it is written to the GUI logs as follows (FGLGUIDEBUG output):
... _om 123{}{{LogEvent 41 {{data " ... free-text ... "}}}}

The typical usage is with the Genero Ghost Client (GGC) tool, to implement non-regression tests: When running a program with a GUI front-end, a LogEvent can be triggered with the Alt-F12 key. The LogEvent events in the GUI log are then reused by GGC, for example to generate snapshots of the AUI tree.

For more details, see the documentation of the Genero Ghost Client (GGC)