Just as a quick update, I’ve done some testing of S5 1.2a1 in the latest version of Opera I have available (which, under OS X, is version 8.51). I’m happy to report that this copy of Opera has all of the S5 features supported in other browsers. Incremental display, font scaling, keyboard navigation, and even the notes window are all present and account for.
To use the notes feature, here’s what I do. Upon loading the base slideshow into Opera, I position the window on my secondary monitor, which is here taking the role of an LCD projector. Then I hit “n”, causing the notes window to appear on my laptop’s monitor (in the role of the presenter’s machine). After bringing the slide show window back to the fore, I select “Full Screen” in the “View” menu, and the presentation maximizes itself to the secondary monitor. As I navigate through the slide show, the notes window stays perfectly synched with the presentation.
There may be better ways to get the notes window on the primary monitor and the presentation on the secondary monitor, but that one worked for me.
If there are problems in Opera 8.5 or Opera 9 that my testing didn’t uncover, let me know. I’ll fix anything I can—and if there’s anything I can’t, I’ll turn it over to the Opera community to figure out. Members of that community have already been invaluable in figuring out how to work around bugs in Opera’s CSS handling in order to make the controls available, so I’m confident they’ll be able to handle anything I can’t figure out.