Publications in other social networks

Juicebox-Pro does not support vk.com. The social media sites supported by Juicebox-Pro can be found here.

It would be possible to manually implement a vk.com (or other social media) share button but knowledge of HTML, JavaScript and the social media's own API would be required (and the share button would need to be positioned outside the gallery and would not be part of the gallery's Button Bar).

You would first need to create a HTML button (or text or image) to act as your share button.
You would then need to fetch the required information from the image currently being displayed in the Juicebox-Pro gallery (the image to be shared) using the Juicebox-Pro API.
You would then need to pass this information along to your chosen social media site via a share URL (the syntax of which would be determined by their own API) when your custom share button is clicked.

All this code would be entered within the text editor (in 'Source' mode) on your Showkase page.

This is certainly possible but perhaps not easy to achieve.