Template extensions was a new developer feature introduced in Piwigo 2.x that makes customization easier. Flop_style, as one such extension, allows display modifications in Piwigo.

What's in flop_style?

11 tpl files:
flop_style/mainpage_categories/captify_mini.tpl
flop_style/mainpage_categories/jPolaroid.tpl
flop_style/mainpage_categories/medium_cat.tpl
flop_style/mainpage_categories/mosaic.tpl
flop_style/mainpage_categories/picpile_cat.tpl
flop_style/mainpage_categories/polaroid.tpl
flop_style/mainpage_categories/popout_details.tpl
flop_style/mainpage_categories/spotlight.tpl
flop_style/thumbnails/fancy_hover.tpl
flop_style/thumbnails/jPolaroid.tpl
flop_style/thumbnails/polaroid.tpl

How to install?

-download the zip, put the folder flop_style and its content in the folder template-extension/ of your gallery
-in your administration, go to Configuration->Templates or admin.php?page=extend_for_templates, if you prefer
-in Original templates select the name of the sub-folder of the template of flop_style (e.g. for flop_style/thumbnails/polaroid.tpl select thumbnails.tpl)
-the 2 others parameters are optional: keep them empty to apply the template to the whole gallery and all themes

See the screenshot on this page to have an idea of what is inside!