Named action for search not working in addon version

[timvandermeij]

http://www.informatik.uni-freiburg.de/~frank/ENG/beamer/example/Beamer-class-example1.pdf

Was caused during review at #3057 (comment). Now, in the addon, nothing happens when clicking the magnifying glass, only in the github.io version it's working. We should always use the Firefox find bar where possible, and otherwise the PDF.js find bar. We can use the method from https://github.com/mozilla/pdf.js/pull/2485/files#diff-0 for this purpose.

@yurydelendik Since you did the review for the named actions PR, what do you think about this?

[yurydelendik]

I'm looking at that from Firefox product point of view: why would some web page is allowed to show/hide UI controls on the browsers? Security implication must be considered for this issue and #2485 pr. (In case of find functionally the browser has full control of its controls)

[timvandermeij]

Closing since in all these years this hasn't been brought up anymore and there are indeed security/usability requirements to consider for this. Finally, this now needs to be fixed upstream and not here anyway.