The 'getDbIndex' function retrieves the position number of a database listed on the Tab Control.
- Prototype: plugin.getDbIndex(sDbPath);
 - Parameters:
- sDbPath: full path to the .nyf database file.
 
 - Return Value: a position number of the database; -1 if not matched.
 - Example: 
alert(plugin.getDbIndex('/home/username/test/1.nyf'));