Found out about this recently for LibreOffice:
Forcing the user to click on a Slide Control to advance to another slide
We must make sure that the user can only proceed from one slide to another
by clicking a Slide Control. As it is, when the user clicks the mouse anywhere
on the slide, the show will advance to the next slide whether it’s supposed
to go there or not.
So here’s how you give the user no option but to click on a Slide Control in
order to proceed.
In the Slide Sorter View, hit Ctrl-a to select all the slides, then in the
Slide Show menu select Slide Show Settings… to bring up the Slide Show Settings
dialog box (Fig. 10.47)
The Slide Show Settings dialog box
Check only the Radio buttons next to Range > All slides and Type > Default,
then, in the Options section, make sure you only have check marks next to
Mouse pointer visible and Animations allowed—NOTHING else should be checked!
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