### Bug description

It happens inconsistenlty, but sometimes when I preview a revealjs presentation, the Speaker View ("S") command doesn't work. If I type "?" for the list of keys, it's not available. 

![image](https://user-images.githubusercontent.com/7606540/217268578-adfd0623-5a75-4f53-b957-775f0dacaeb1.png)

The solution is to save the presentation source (in VSCode) and quarto runs again. Alternatively, I can kill the preview process and re-do the preview. Again, this doesn't always fix the problem, but when it does, the "S" command is at the bottom of the help list (see below) and it works as expected:

![image](https://user-images.githubusercontent.com/7606540/217270360-a2328f27-8091-4866-aebe-5e05fc72c511.png)

I'm not always using `multiplex` in my presentations with students (it's useful for online, low bandwidth), but by setting `multiplex: false`, it seems to fix the behavior. I suspect it's a race condition with loading modules in the browser. Maybe the `multiplex:true` is not compatible with speakerview in preview mode? Again, I thought it worth documenting.

I'm on Windows 10, using Chrome, doing previews with `quarto preview my-presentation.qmd --to revealjs`. Quarto is version 1.3.146. 

I didn't do enough tests to find the frequency, but my gut says it's like a 50% chance of happening. When I couldn't reproduce with a vanilla presentation, I found the `multiplex: true` as part of the puzzle. See the MWE at https://github.com/fuhrmanator/quarto-test/blob/d1eee4019a0af025ab325997318cf87c6586ebf8/revealjs-test/test.qmd

### Checklist

- [ ] Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
- [X] Please [format your issue](https://quarto.org/bug-reports.html#formatting-make-githubs-markdown-work-for-us) so it is easier for us to read the bug report.
- [ ] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] Please document the operating system you're running. If on Linux, please provide the specific distribution.
cderv
2023-02-07T14:48:28Z
fuhrmanator
bug revealjs
v1.4
open
Quarto preview of revealjs sometimes doesn't have speakerview when `multiplex: true`
https://github.com/quarto-dev/quarto-cli/issues/4258