The ability to pan and zoom when viewing photos in the lightbox on Google+ has been around since the day before we launched (January 9 2013), using the scroll wheel to zoom and your cursor to navigate. Though, it wasn't until recently (last week) that the button to activate the feature without initiating via the scroll wheel, had been added to the lightbox, sitting comfortably next to the rotation tool or "More" menu, depending if you're viewing your own photo or not. The magnifying glass icon will change from positive and negative indicating if you're zoomed in or out, which is fine and dandy for accessibility reasons.
Most likely, the reason a button to activate the feature had been added was due to many users not knowing that the pan and zoom ability even existed, which makes sense as there were no hints that the feature was there previously.
I think I've covered everything, which isn't much due to the relatively minor update, but it's always good to know! Thanks to our hard-working moderator, +Simon Janssens de Varebeke for spotting and reporting the update in our community.
What do you make of this little new addition? Add a comment and let us know!