Occurs when a document requires password for opening.
Definition:
extractor.password_required+=handler# subscribe handler(sender, args)extractor.password_required-=handler# remove the last subscription of handlerextractor.password_required.clear()# remove every handler added from Python
The handler runs on the thread that raises the event, which can be an engine worker thread. An exception it raises there is printed to stderr and ignored; on the calling thread it reaches the engine, as in .NET.