With the new Mathematica 11.3 File > New > Presentation notebook, it’s easy to create a slideshow quickly. But once you click the notebook’s Start Presentation button, on a Mac I see no obvious keyboard-only way to navigate (without having included a navigation bar at the top of each page and without using either the obtrusive drop-down menu an obtrusive navigation palette).
The Presentation Controls pop-up, available while the notebook is still in Slideshow Working as Screen Environment, lists the default navigation keys, which Page Up and Page Down for previous and next slide, respectively; and Home and End for first and last slide, respectively. That’s just fine on a Windows PC, where there are such keys. But a standard Mac does not have these keys!
It’s easy to change the controls for previous and next page to left arrow and right arrow there. But what about first and last slide? Ordinarly on a Mac, Fn-left arrow and Fn-right arrow give the equivalent of Home and End. But this does not seem to work with a slideshow presentation.
I was able to get this to work after a fashion on my MacBook with Fn-Up arrow and Fn-Down arrow (previous and next slide), and command-up arrow (first slide) and command-down arrow (last slide). That’s not exactly what should be happening as you note, Fn-left and right arrows should work but don’t (see Mac keyboard shortcuts – Apple Support (UK)).
In any case, the best thing for now may be to remap the keys from the provided list so that you’re not dependant on such awkward key combinations.
When I clicked on “Toggle Navigation Bar” I got the standard navigation elements at the top of the slides. In the same place under the “Presentation Controls” I used this
Yes, I know about all that. The issue was to get suitable keys to work. But bare Up Arrow and Down Arrow seems to be not a totally satisfactory choice for first slide and last slide, given that one is more like to want to reserve them for navigating through a particular slide.
Those key combinations work for me, too. A good compromise would seem to be to leave Home and End as first slide and last slide, which on Mac will be Cmd-Up arrow and Cmd-Down arrow, respectively. And to change Previous slide and Next slide to left arrow and right arrow, respectively.
Alas, neither of those pairs of choices to go to first and last slide is suitable – assuming that one wants a slideshow in Mathematica still to allow actual interactivity, including adding or altering input there on the fly. For example, suppose it’s appropriate in the middle of a presentation to add:
f[x_] := Exp[-x] Sin[x^2]
f'[x]
Oops: that would take you immediately away from the Input cell where you were working!
(And for the same reason, one would not want to use the letters “f” and “l”, as you realized. E.g., if you wanted to add input such as a Plot expression, or to define a function named f.