Notices

Is there any other site that you know of like this that would work with Tear?
http://downloadyoutubevideo.org/

The contextmenu event is emitted by Tear, and it can be canceled. I use jQuery and implemented the cancellation like this:
That table does not clearly cite which version(s) of Webkit are being tested. The dblclick event is generated within Tear, but I think it has a small time threshold and a small position-change tolerance.

Does Tear support local user stylesheets, like Mozilla's user.css? If so, where does that stylesheet reside?

Yep, Tear supports user CSS and stylesheet is in /home/user/.tear/userstyles.css

Tear and google plus:

with the default user agent, google tells me that the browser is unsupported.
If I spoof the ipad user agent, it redirects to the mobile site which doesn't work.
If I spoof the firefox 5 user agent, google plus works (it's slow but it works) but I lose the ability to scroll with the d-pad in google reader.
Restore the default user agent and the d-pad works again.

My N800 doesn't boot lately, I'll check if I'm able to.

I tried the safari user agent:

and both google plus and scrolling with the dpad work.

Frankly, I though that google was better than this and didn't have to resort to user agent sniffing.
Google- instead of Google+

IMHO it's perfectly ok that Google+ behaves differently based on User-Agent. This is not bad will of Evil Inc. to create problems to a couple-and-a-half of geeks who use Tear. This is side effect of efforts ofGoogle+ Team to do best for majority of users of that vast variety of browsers and platforms.
There are plenty of desktop browsers and even much plenty of mobile ones. And mobile browsers are much less standardized and every single browsers does these tricks like drag-to-scroll, longtap-to-rightclick, pinch-to-zoom in different ways. So webdevs have to adopt their sites to work with all this zoo.
And this is just true that Tear behaves more like iPhone's mobile Safari than regular (read: desktop) webkit browser.

I'm not very experienced in web development, but I think user agent sniffing is a very poor way to assess browser capabilities.
Even if they go for the UA sniffing, don't block me outright, just tell me that the site won't probably work properly but let me in.
BTW, with the mobile safari user agent, google plus doesn't work at all in tear.
Frankly, I expect google to be more competent than your typical groceries chain.

If you know better way to obtain browser capabilities than checking its UA, please tell me because i don't.
Different browsers behave differently, this is reality and you can't do anything with it. As webdev you must build your code to handle with it. And you need to sniff UA to know how to deal with given browser.
In what order will it generate all these mousedown, mouseup, mousemove, mouseenter, mouseleave while user does drag-n-drop?
Will it generate left-button-up event before right-button-down when user does long tap in mobile browser?
Does it support CSS3 with border-radius, gradients and CSS transitions? (server should generate completely different html depending on this)
Does it use W3C box model or MS's one?
Does it support dropping file onto html page?
Needless to say about all these 1px differences while handling floats, negative margins, etc.
You can build some sites universally without this knowledge. But not really complex things.
So, UA sniffing is okay. It is sad, of course, that servers have to resort to such ugly way, but this is reality and you can't blame webdevs. This is not lack of competence. On the contrary, this is indication of their competence and amount of human-hours spent to adopt their site to work best on most popular browsers.

Another question is how to deal with unsupported browser (or browser google just havn't tested their site with). I agree that there should be some link saying "ok, it will be broken but let me in anyway" like it was in Google Docs.
But this is matter of marketing and politics. Many ordinary users will think better about Google if G+ will say "Sorry, your device is unsupported, plz use G+ on your desktop" than if it will let them in but give them completely broken experience. Because in this case they will say "G+ site is broken and unreliable and G+ developers are not smart enough to fix these obvious bugs".
This is not about geeks, this is about regular users. You know, many, many of them will never understand these strange statements like "THIS SOFTWARE IS PROVIDED "AS IS" AND WE DON'T GIVE ANY WARRANTY". But they will kindly understand "Sorry, your rare and unusual device is unsupported" just like they understand that their tiny mp3 player doesn't support CD discs and magnetic tapes.

Sorry for offtopic