It would be great to be able to match the built in PDF editing tools that Microsoft Edge has, specifically the highlighting and drawing tools. This is one of the reasons I can't use Firefox for working with PDFs.
A webbrowser is not a "PDF viewer/editor" and should not be bloated with the addional functionality.
People might like the idea because it would fit their workflow but convenience should not superseed purpose/design or security aspects.
I am fine with it being an optional protocol, which extension can handle/render ... but not everyone wants or needs their pdf reader to be integrated into the browser.
It seems that posts like these are opened for each content-type found on the internet. (EPUB, ISO, Torrent, ...)
I really hope mozilla will soon extend the protocol and content-type handling functionality for the web-exentsion API. Than these posts ... should vanish by themself.
Additionally, if a simple presenter view would be added to that reader, for example to be used with Beamer presentations, witch included a Clock/Timer/Countdown and slide splitting to be used in the way Pacien (GitHub https://github.com/pacien/beamer-viewer) did, would be absolutely great and different. I love the reveal.js speaker's interface design too.
Thank you everyone for your idea and suggestions, we are starting to build some basic PDF editing features. Initially we will support inserting text, with color and font size selection, and drawing, with color and line thickness selection.
The feature is currently available in Nightly behind a pref, you can test it out if you want, but do take into account that the UI/UX will likely change.