You need to select a database connection before you can perform these operations. For example, select the database connection you want to edit by clicking on it, then click on Edit.
Visual Explain is designed to run only as a single copy. The first copy creates a lock file that prevents other copies from saving configuration data. All other functions behave normally.
If Visual Explain abnormally shuts down, the subsequent restart may give a warning about an existing lock file. In this case, remove the lock file and restart Visual Explain.
The EXPLAIN button remains disabled until you have established a connection to a database.
If you use the Sun 1.3 JRE/JDK with rhdb-explain, you may see messages about key binding errors. The messages are incorrect--the key bindings actually work. However, if you use the Sun 1.4 JRE/JDK instead, there are no error messages.