Re: [Usability] link handling

[Matthew Paul Thomas <mpt myrealbox com>]

On May 10, 2007, at 6:50 PM, André Wyrwa wrote:
> ...
> If i get a mail with a link to a pdf file, firefox opens and presents  
> me with an empty window directly opening evince to show the document.
>
> Since Evince can open the pdf from the web directly, it would be much
> nicer if Evolution would directly open Evince.
>
> More generalised: It would be great, if all links to files other than
> web pages would directly open the mime-associated application, provided
> that they'd be capable of fetching the content (via gnome-vfs)?
> ...

That would be nifty, but probably not possible. The flaw in the plan,  
as you suggested, is that it "would exceed the possibilies of current  
mime specifications". More precisely, Evolution can't know that it's a  
PDF, without making an HTTP request for (at least the metadata of) the  
file. You might be thinking that if the URL ends in ".pdf", Evolution  
can trust the file to be a PDF, but it can't. For example,  
<http://www.google.com/search?q=cache:OjBILldOR4sJ: 
crypto.csail.mit.edu/classes/6.857/papers/secret-shamir.pdf> is an HTML  
page, not a PDF.

I could even email you a redirect to that URL, like so.  
<http://urlx.org/google.com/0a8e8> Now Evolution would need to make not  
one, but two HTTP requests just to find out that the file is something  
that Firefox will need to open after all -- and Firefox would then have  
to make those HTTP requests all over again, making the overall  
experience much slower. And even if it *was* a PDF, what if the link  
was to a site that requires cookie-based logins for downloads? Firefox  
would be able to handle the login (indeed, if Firefox was your usual  
browser it probably would have the necessary cookie already), but  
Evince would not. (That part of the problem would be solved if Gnome  
programs shared cookies and if you were using a Gnome-based Web  
browser, but neither of those are true.)

So the next best thing is for Firefox, if it opens a new window/tab  
solely to display a file that ends up being handed off to a helper app,  
to close that unused browser window/tab immediately. Other browsers do  
this; if Firefox doesn't, you should report that as a bug.

(You may think, "why doesn't Firefox delay opening a new window/tab  
until it knows that it's downloading a file that it can display  
itself?" But very early Mozilla versions actually did work that way,  
and it was horrible. When Web sites were slow in responding, it looked  
like it was the browser that was slow, or like Mozilla had ignored the  
mouse click altogether.)

Cheers
--
Matthew Paul Thomas
http://mpt.net.nz/