LOL I have firefox 9 installed (which I think the latest stable emerge for linux is 13.0.1). Mostly this is about "what's the deal with the major revisions".
Which reminds me I need to look up what's needed to make a plugin, I was thinking it would be nifty making an X plugin for remote display in Firefox. Maybe tweak Evince as a PDF viewer as well

(hmm might work).
Cyb - anyhow it's a long road sometimes.
A further update, I've been testing firefox and as noted by Toasty they are making a 'built in plugin' here is why.
It appears the Adobe PDF plugin is unstable to a large degree. Most of this appears to be internet access related (IE reading data from the originating site). I know Adobe likes to track things so I suspect part of it is 'a dial home for the latest' and also just a dial home mechanism. IE you loaded a PDF and they are doing idiot stuff (mostly idiot stuff really is a better term). I've noted this as Firefox has died recently several times under XP but the linux version doesn't (as it doesn't use the Adobe plugin). The Adobe plugin likely assumes it should not play nice (IE do a little bit and relinquish some time back).
Partly too blame is how windows handles threading and processes in general I suspect. Just a suspicion but it can't be corroborated so 'not fact'.
Cyb
addendum 2
I did test the mozilla PDF toy. It has some definate flaws:
1: it has no internal rendering instead it uses HTML5 do to the work
2: It is hard to recognize what icons do what (without 'helper' labels which it lacks)
3: it lacks a traditional TEXT based menu (IE if you can't understand the icons you could use a menu to select options)
4: Index or Preview control is lacking, this is a serious flaw since much of what I am reading in PDF form may have 1200 or more pages in it. It may indicate that it is still "GET IT DONE" mode of thinking. Correction the icons are too blame, they are horribly undichipherable and thus hard to follow. I acidentally found it.
5: More On icons, I'm not sure why they choose the icons but you can't switch cleanly between indexed preview and none cleanly. In addition the icons are designed for visual appeal not usability. The next is more egregious they obviously did not use the settings from the browser (IE font scale) or are even clued in on display resolution. I have a high resolution display (2 1920x1200 side by side 24 inch displays) it is a total <censored> to read things if they decide the scale of things based on pixels in there icons and menus. Although the icons would be probably fine at 1024x 768 they aren't at higher resolutions. Although Beta that is actually paramount in any design that is for presenting visual data (IE reading). I'm not whining read this carefully eye strain is serious if you have high rez monitors I've found, you have to be extremely careful otherwise you get lost on your screens trying to find the idiot cursor because some moron decided to make it 'pixel' sized and not 'pitch' sized (pitch refering to the dpi of your display so that it would be sized so it could be spoted easily in all cases). Let me put it this way I can barely see the cursor with what I'm editing right now because of it.
6: it appears they used the TAB icon size for icons (when it would have been better to use bigger uglier buttons for everyone to easily use of course someone would complain about it \mostly people who don't read a lot of pdfs I suspect\). looking at it proportionately it looks kind of odd
7: lack of prefered default settings. PDFs have 3 sets of settings (surprised?) one is the set the people who made the PDF wanted (which I have found are usually not what I want) and then the settings YOU the user wants and lastly the default settings. It appears the PDF only supports the latter (shrug) somewhat annoying. It has no preferences you can set so you can't overide it's defaults. The majority of PDFS have set whole page and either indexed or preview for pages for a side bar.
Positives:
1: it does work
2: I can block it from working which is handy because some websites do not distinguish between a PDF source and a web source (at all) so that was an unexpected bonus of using it
3: the things that are labeled are labeled in a correct font
4: the rendering of the PDF is decent (which I've found to be an issue with most open source variants of PDF viewers because they tend render things as bit map data instead of vector data) it appears to scale without odd pixelation (reminding me of JPEG decompression from using a DCT or something odd like that).
I don't know if anyone will find my review useful but hopefully they will consider that PDFs sometimes are in the thousands of pages long before murderous attempts at rendering an entire PDF (into bitmaps) at one particular resolution or something (which would be ... seriously huge several gigabytes easily).
To show you want I'm talking about
here is a typical data sheet I have to page through (medium sized).
Cyb - back to work