Feature: overlay buttons with click events as plugins

[supersexy]

It would be extremely useful if we could implement overlay buttons with click handlers, e.g. for sharing or rating pictures or doing anything related to user interaction.

I believe it would make sense if you decided how to implement such optional overlays in a way that it still is extensible, so people could add their own "button action plugin" easily.

Do you think this is interesting?

[BenjaminBrandmeier]

Absolutely. I'm willing to merge a PR if you or anyone else is willing to contribute on this matter.