The idea is to have a "play" button or something in the
popup and in every section with content, and when
clicking it start a slide show of all images in that
section.
If it is pressed directly in the section view (where
you can see the thumbnails of the images in that
folder) a popup will open, and it will display the
first image of the section for a stablished period of
time; when that time is up, it will switch to the next
image in the section, and so on until it reaches the
last one.
When pressed from the popup, it will start the slide
show, but starting with the current image.
Slide show delay could be customized in the section
view, having a predefined value setted up in the config
file.
Another setting could be "cycle", to never stop the
slideshow, and restart after the last image is shown.
Fullscreen will be another interesting option for the
slideshow, with the option to stretch images.