Please consider the following:
Add rollover info on icon to let one know what it does,
Add "unsupported" when trying to open a file with an external app or extension that is not supported,
Consider showing zoom value under "zoom slider".
I would like to say that Peakto is the only phot library I have and would ever consider.
It's features and flexibility is way above any other photo library platform I have seen and would highly recommend it to all.