As demonstrated by
getSelectedSlideIndex() from sample https://raw.githubusercontent.com/OfficeDev/office-js-snippets/prod/samples/powerpoint/preview-apis/tags.yaml it is easy to determine the currently selected slide.
I need my PowerPoint add-in to be able to change the currently selected slide.
This is e.g. useful after inserting a slide, in order to show it to the user.
Also changing the currently selected shape on the active slide would be beneficial.