Deal gracefully with elements that have no computed style available

[jmcphers]

No description provided.

[jjallaire]

@yihui, @wch, and @jcheng5, is this something we can get into v0.10.1? (it fixes a pretty fundamental problem with shiny widgets (embedded apps) in ioslides presentations).

[wch]

Sure, it looks OK to me. Do you mind adding a comment about which browsers you've encountered that have this behavior?

[yihui]

Yep, looks good to me, too.

[jjallaire]

Here is the original issue where it was tracked in rmarkdown (some notes about browsers there):
rstudio/rmarkdown#184

@trestletech or @jmcphers do you have anything to add about where/when this issue was encountered?

[fereshtehRS]

I have seen the issue mostly with Firefox (FF 31 on Mac and FF 23 on Ubuntu).

[jmcphers]

This appears to be the offending bug in Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=548397. I've updated the comment.

[wch]

Great, thanks!

[fereshtehRS]

I installed the latest shiny package, and see improvement on this issue using Firefox, but not completely fixed.
I am using the presentation document via Shiny Server.
My presentation has 3 embedded shiny apps on pages 6, 7, and 8. Previously if I paged through the slides none of these apps would be loaded. Now, when I page through the slides, apps on pages 6 and 7 are loaded, but app on page 8 still not loaded.

[jmcphers]

@fereshtehRS , thanks for testing the fix so promptly. I can't reproduce the problem on my end with > 10 apps, so maybe specific to something in the app on page 8--does that app work if it's on page 6? Can you share your presentation?

[fereshtehRS]

I only see this with Firefox (my version is 31). Emailed you the presentation.
The app loads fine if I am on that page (page 8) and refresh browser. It is only a matter of paging through presentation slides.
I can see this through Shiny Server and local Shiny.

[tareefk]

There may be more than one place that this happens. I was talking with Winston and with the CRAN version of Shiny you can see this error in Firefox.

Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help http://xhr.spec.whatwg.org/ jquery.js:9627
syntax error token:1
TypeError: window.getComputedStyle(...) is null selectize.min.js:2

[wch]

I found this in selectize.min.js:

e=window.getComputedStyle?window.getComputedStyle(f,null).getPropertyValue("direction"):f.currentStyle

So it's the same issue as Jonathan fixed in shiny.js. It looks like we'll need a customized version of selectize, unless they've fixed it in recent versions.

[jcheng5]

It's not fixed but we could submit a PR.