In order not to break multi-picture tiling (there would be gaps) the images would have to be shown sequentially:
pic1 pic2 pic3
This can be achieved with pure CSS using Stylish or similar addon/extension:
@-moz-document domain("facebook.com") {
._2a2q,
._2a2q > a,
._2a2q > a > div,
._2a2q > a > div > img {
width: 100%!important;
height: auto!important;
position: static!important;
}
}
I tested it just on a couple of pages though.
P.S. you might want to use the awesome Mouseover Popup Image Viewer userscript instead.
Facebook: Uncrop images in news feed
Problem: Facebook "crops" images uploaded by other users when displayed in the news feed, forcing you to click on them and open them in a new window to view the whole thing. I would like a userscript that causes Facebook to display the WHOLE picture, always, no cropping, no manipulations.