Feature request: quick access to frequently used images as overlay on any slide

[nucleic-acid]

Usecase

When discussing a complex process in a specialist training or e.g. presenting in a scientific context, you might walk the audience through a long, complicated process, one detailed step after another. While it makes sense to split these steps into separate slides, the audience might loose orientation, where in the said process you are.

Think of e.g. of a scientist explaining a metabolic pathway where genes, enzymes and metabolites interact on different levels in different ways. In addition the presenter might want to mention in what different organs these steps take place. At the moment you could put schematic drawings on a slide and jump back and forth in the talk when questions arise or you could repeat the schematic slides at predefined positions in the slide deck.

If the presenter had 2-3 images with frequently needed schematic overviews quickly accessible on all slides, he could temporarily open it up, point to the section he is currently talking about, and then continue with his slide. He might also frequently open up an image, to keep some other fact in active memory of the audience.

Suggested solution

Provide a "Quick-Access-Inventory", where few image files can be stored. This inventory would be viewed as a small icon in a corner or in a sidebar on every slide (similar to the search icon or other xaringanExtras). Clicking on it or via Mouse-over you could expand the inventory to see thumbnails of the pictures. You can then select an image, which is overlayed over the current slide (the current slide might e.g. become grayed out in the back). The presenter might use the overlay image to show the current position within the complex process, answer a question or point to associated other parts in the process that are related....
Clicking on the overlay image closes the overlay and the presenter can continue with the talk.

Expected Improvement

Whenever the presenter feels the need to take a step back and give the audience an overview, answer a question from the audience regarding the overall picture or point to different parts of the process, he can fire up the inventory whenever needed, without having to go back and forth between slides.