This is a really weird request.. I'm trying to transition my mum away from Aperture *before* it eventually breaks but she's so used to being able to select a bunch of photos to bring them up at once and compare them side by side.. I botched together a system where she can multiple select/edit in/Preview but that requires a lot of faffing about moving preview windows, making it full screen, etc.. Not what preview is for - even in "contact sheet" mode it's not ideal.. I might want a single purpose app that opens the selected pics all in one window as big as they can, with the ability to zoom and pan around them.. Is there some obscure image viewer that's flexible enough to do this? People have been asking for this sort of feature for Photos for years and Apple seem to shrug it off (despite it being super useful for multi display set ups!) - I cant think of anything other than a work-around.. Thanks in advance!