No specific info about version 5.1. Please visit the main page of FastStone Image Viewer on Software Informer.
Guys this is a great tool, try it! I use it for many years and is still the better photo manager. Full of very usefull features with a nice photo-resizer.
Only 1 problem: the vector graphics formats are missing (.eps, .ai, etc.).
Version 4 of this was brilliant but recently downloaded and installed version 5 and wish I never had it. It's very resource hungry and often hangs.