user-level interaction with multiple sets (matrix)

[paxperscientiam]

What do you think, @rejas, of allowing for the creation of a 2D imageLightbox? Basically, there is some trigger to open two or more imageLightbox sets. While the 'left' and 'right' actions will continue to work as they do now, 'up' and 'down' actions would switch user-level interaction to another imageLightbox.

This basically piggybacks off of #92 EDIT: Also piggy backs off of #91

[rejas]

very interesting idea if it can be done without too much growth in size :-)