Posts in the Tech Category

In the course of a recent debugging session, I discovered a limitation of web inspectors (Firebug, Dragonfly, Safari’s Web Inspector, et al.) that I hadn’t quite grasped before: they don’t show pseudo-elements and they’re not so great with pseudo-classes.  There’s one semi-exception to this rule, which is Internet Explorer 8’s built-in Developer Tool.  It shows pseudo-elements just fine.

Here’s an example of what I’m talking about:

p::after {content: " -\2761-"; font-size: smaller;}

Drop that style into any document that has paragraphs.  Load it up in your favorite development browser.  Now inspect a paragraph.  You will not see the generated content in the DOM view, and you won’t see the pseudo-element rule in the Styles tab (except in IE, where you get the latter, though not the former).

The problem isn’t that I used an escaped Unicode reference; take that out and you’ll still see the same results, as on the test page I threw together.  It isn’t the double-colon syntax, either, which all modern browsers handle just fine; and anyway, I can take it back to a single colon and still see the same results.  ::first-letter, ::first-line, ::before, and ::after are all basically invisible in most inspectors.

This can be a problem when developing, especially in cases such as having a forgotten, runaway generated-content clearfix making hash of the layout.  No matter how many times you inspect the elements that are behaving strangely, you aren’t going to see anything in the inspector that tells you why the weirdness is happening.

The same is largely true for dynamic pseudo-classes.  If you style all five link states, only two will show up in most inspectors—either :link or :visited, depending on whether you’ve visited the link’s target; and :focus.  (You can sometimes also get :hover in Dragonfly, though I’ve not been able to do so reliably.  IE8’s Developer Tool always shows a:link even when the link is visited, and doesn’t appear to show any other link states.  …yes, this is getting complicated.)

The more static pseudo-classes, like :first-child, do show up pretty well across the board (except in IE, which doesn’t support all the advanced static pseudo-classes; e.g., :last-child).

I can appreciate that inspectors face an interesting challenge here.  Pseudo-elements are just that, and aren’t part of the actual structure.  And yet Internet Explorer’s Developer Tool manages to find those rules and display them without any fuss, even if it doesn’t show generated content in its DOM view.  Some inspectors do better than others with dynamic pseudo-classes, but the fact remains that you basically can’t see some of them even though they will potentially apply to the inspected link at some point.

I’d be very interested to know what inspector teams encountered in trying to solve this problem, or if they’ve never tried.  I’d be especially interested to know why IE shows pseudo-elements when the others don’t—is it made simple by their rendering engine’s internals, or did someone on the Developer Tool team go to the extra effort of special-casing those rules?

For me, however, the overriding question is this: what will it take for the various inspectors to behave more like IE’s does, and show pseudo-element and pseudo-class rules that are associated with the element currently being inspected?  And as a bonus, to get them to show in the DOM view where the pseudo-elements actually live, so to speak?

(Addendum: when I talk about IE and the Developer Tool in this post, I mean the tool built into IE8.  I did not test the Developer Toolbar that was available for IE6 and IE7.  Thanks to Jeff L for pointing out the need to be clear about that.)

• Pseudo-Phantoms was published on Tuesday, November 3rd, 2009.
• It was assigned to the Browsers, CSS, DOM, Tools, and Web categories.
• There have been nineteen replies.

I mentioned in my previous post that I “had come away with my head reeling from the massive length and depth of the often-changing specification”, which is entirely true.  Printouts of the current draft of the HTML5 spec can reach, depending on your operating system and installed fonts, somewhere north of 900 pages.  Yes: nine hundred.  There are unabridged Stephen King novels that run shorter.

You might well say to yourself: “Self, is it just me, or are the people doing this completely off their everlovin’ rockers?  Because the specification for something as fundamentally simple as HTML should reach maybe 200 pages, max.”  You might even despair that the entire enterprise is doomed to failure precisely because nobody sane will ever sit down to read that entire doorstop.

But there’s no real reason to panic, because here’s the thing about the HTML5 specification that might not be obvious right away:  it’s not for you.  It’s for implementors.  And that’s a good thing.

If you do start reading the HTML5 draft, you’ll start running into really lengthy, excruciatingly detailed algorithms for, say, parsing a time component.  Or moving through the browser’s history.  Or submitting a form.  There’s an entire (long) chapter on how to process the HTML syntax.

Those are all good things, actually.  They greatly increase the chances of interoperability actually happening within our lifetimes.  There’s no guessing about, well, much of anything.  It’s all been exactingly defined, to the extent that one can exactingly define anything using a human language.  A browser team doesn’t have to wonder, or even guess, what to do when the document has been completely parsed.  It’s all spelled out.  And the people on those browser teams will, in the end, be the people who read that entire doorstop.  (Their sanity is another matter, and not discussed here.)

How is all that stuff relevant to you, the author?  In the sense that when browser teams follow the spec, their products will be interoperable, which is to say consistent.  (Just imagine that for a moment.)

Beyond that, though, the detailed implementation stuff isn’t relevant to you.  You are not expected to know all those algorithms in order to write HTML documents.  Pretty much all you need to know is the markup.  That’s the part that should be no more than 200 pages, yeah?

Turns out it is, and by a comfortable margin.  Michael(tm) Smith’s HTML5: The Markup Language is a version of the HTML5 draft with all of those eye-wateringly pedantic implementor sections stripped out, and when I generated a PDF it came in at 147 pages.  That’s what you really need in order to get up to speed on what’s in HTML5.  It’s for you.

• HTML5 And You was published on Monday, September 7th, 2009.
• It was assigned to the (X)HTML, HTML5, Standards, and Web categories.
• There have been eighteen replies.

Like so many others, I had tried to dig into the meat of HTML5 and figure out just what the heck was going on.  Like so many others, I had come away with my head reeling from the massive length and depth of the often-changing specification, unsure of the real meaning of much of what I had read.  And like so many others, I had gone to read the commentary surrounding HTML5 and come away deeply dispirited by the confusion, cross-claims, and rancor I found.

Then I received an invitation to join a small, in-person gathering of like-minded people, many of them just as confused and dispirited as I, to turn our collective focus to the situation and see what we found.  I already had plans for the meeting’s scheduled dates.  I altered the plans.

Over two long days, we poked and prodded and pounded on the HTML5 specification—doing our best to figure out what was meant by, and what would result from, this phrase or that example; trying to reconcile seemingly arbitrary design choices with what we knew of the web and its history and the stated goals of the HTML5 specification; puzzling over the implications of example code and detailed algorithms and non-normative notes.

In the end, we came away with a better understanding of what’s going on, and out of that arose some concerns and suggestions.  But in the main, we felt much better about what’s going on in HTML5, and have now said so publicly.

Personally, there are two markup changes I’d like most to see:

1. The content model of footer should match that of header. As others have said, the English-language name of the footer element creates expectations about what it is and how it should work.  As the spec now stands, most of those expectations will be wrong.  To wit: if your page’s footer includes navigation links, and especially if you have an HTML5-structured “fat footer“, you can’t use footer to contain it.

   If this feels a little familiar, it should: the same problem happened with address, which was specified to mean only the contact information for the author of a page.  It was quite explicitly specified to not accept mailing addresses.  Of course, tons of people did just that, because they had an address and there was an address element, so of course they went together!

   A lot of us cringed every time this came up in the last ten years of conducting training, because it meant we’d have to spend a few minutes explaining that the meaning of the element’s name clashed with its technical design.  We saw a lot of furrowed brows, rolled eyes, and derisively shaken heads.  That will be magnified a millionfold with footer if things are allowed to stand as they are.

   As I said, the fix is simple: just change the content model of footer to state:

   Flow content, but with no header or footer element descendants.

   That’s exactly the same content model as header, and for the same reasons.

2. time needs to be less restrictive.  That’s not very precise, I know.  But as things stand now, you can only apply time to Gregorian datetimes, and you’re not supposed to use it for anything that couldn’t be easily represented in a calendaring program.  The HTML5 specification says:

   The time element is not intended for encoding times for which a precise date or time cannot be established.

   That makes me wonder, in a manner not at all like Robert Plant, how precise do we have to be?  The answer, I’m sorry to say, is too much.

   To pick an example: I have what I think of as a great use case for the time element, and while it uses the Gregorian calendar, it’s only accurate to whole months (as is Wikipedia’s version).  In some cases I could get the values down to specific days; but in others, maybe not.  So I can’t use the datetime attribute, which requires at least year-month-day, if not actual hours and minutes.  I could omit the attribute, and just have this:

   <time>October 2007</time>
   

   In that case, the content has to be a valid date string in content—which is to say, a valid date string with optional whitespace.  So that won’t work.

   I’ve pondered how best to tackle this, as did the Super Friends.  Our suggestion is to allow bare year and month-day values as permitted in ISO8601.  In addition, I think we should allow a valid date string to only require a year, with month, day, and time optional.  That seems good enough as long as we’re going to go with the idea that the Gregorian calendar contains all the time we ever want to structure.

   But what about other, older dates, some of which are fairly precisely known within their own calendars?  On that point, though the historian in me clamors for a fix, I’m uncertain as to what.  PPK, on the other hand, has put alot of thought into this and written a piece that I have skimmed but never, perhaps ironically, found the time to read in its entirety.

These are not my only concerns, but they’re the big ones.  For the rest, I concur with the hiccups guide, though of course to varying degrees.  I’m still trying to decide how much I care (or don’t) about the subtle differences between article and section, for example, or the way aside fits (or doesn’t) with its cousin elements.  And dialog just bugs me, but I’m not sure I have a better proposal, so I’ll leave it be for the time being.

At the other end of the two days, I felt a good deal more calm and hopeful than I did going in.  As Jeffrey said, “the more I study the direction HTML5 is taking, the better I like it”.  While there are still rough edges to be smoothed, there is time to smooth them.  We’ve already seen responsiveness on some of the points we addressed in the hiccups guide, and discussions around others.  The specification itself is daunting, especially to those who might remember the compact simplicity of the HTML2 spec.  Fortunately, it has good internal cross-linking so that you can, with effort, track down exactly what’s meant by “valid date string with optional time” or “sectioning content” or “formatBlock candidate“.

With HTML5, the web is not ending, nor is it starting over.  It’s evolving, slowly and in full view of the public, with an opportunity for anyone to have their say (which is not, of course, the same as having one’s proposals accepted).  It’s the next step, and I feel quite a bit more confident that it’s a step onto solid ground.

• Nine Into Five was published on Wednesday, September 2nd, 2009.
• It was assigned to the (X)HTML, Commentary, HTML5, Standards, and Web categories.
• There have been twenty-one replies.

Last week, I got an interesting inquiry from Velda Christensen:

@meyerweb *wondering just how many of your followers follow @zeldman and vice-versa*

I had no idea.  Furthermore, I didn’t know of a tool that could tell me.  So I built one: Followerlap.

As it turned out, the Twitter API made answering the specific question pretty ridiculously easy, thanks to followers/ids.  All it takes is two API requests, one for each username.  The same would be true of friends/ids, on top of which I suspect I’ll fairly shortly build a tool quite similar to Followerlap.

Since I announced Followerlap’s existence on (where else?) Twitter, I’ve had a few repeated (and not unexpected) bits of feedback.

• Why not list the common followers?  Because followers/ids returns a list of numeric IDs.  Resolving those IDs as usernames would require one API hit per ID.  If there are 15 followers in common, that’s not such a big deal, but if there are 1,500, well, I’ll run out of my hourly allotment of API requests very quickly.  Maybe there’s a better way; if so, I’d love to hear about it, because that would be a great addition.

• Why can’t I find out how many people follow both Stephen Fry and Shaquille O’Neal?  Past a certain number of followers, somewhere in the 200,000–250,000 range, the API just dies.  You can’t even count on getting a consistent error message back.  There are ways around this, but I didn’t want to stress the API that way, so it just fails.  Sorry.

• How can I link to a specific comparison?  At the moment, you can’t.  I hope to make that happen soon, but I decided that a tool this simple should have a similarly simple launch.  Ship early, ship often, right?  Anyway, it’s on the list of things to add soon.  Use the new “Livelink to this result” link underneath a result.  (See update below for more.)

So that’s Followerlap.  Any other questions?  I’ll do my best to answer them in the comments, though for a number of reasons I may be slow to respond.

Update 6 Jul 09: as noted in the edited point above, livelinking of comparison results is now, um, live.  So now you can pass around results like the number of people who follow both God and the Devil (thanks to Paul M. Watson for coming up with that one!).  I call this “livelinking” because hitting a result URL will get you the very latest results for that particular comparison.  “Permalinking” to me implied that it would link to a specific result at a specific time, which the tool doesn’t do and very likely never, ever will.

• Announcing Followerlap was published on Monday, July 6th, 2009.
• It was assigned to the Projects, Tools, and Web categories.
• There have been twenty-nine replies.

There’s something about the Diggbroglio that has left me scratching my head:  how is it that so many people are up in arms about the DiggBar when they’ve had nothing to say about the framing bars of StumbleUpon, FaceBook, etc. etc.?

Now, please note that I’m not saying the DiggBar, or any other framing bar, is cool and we should all love it.  I’m not.  I absolutely, completely, totally get all the reasons why framing bars are bad for breaking bookmarking and navigating and search engines and copyright and hijacking content and so on.  But that’s precisely why I’m so confused, because we’ve known for years now that framing bars are bad mojo—and yet StumbleUpon, for example, is based on bars.  There is a browser extension/plugin StumbleUpon thingy you can install, but there’s also a web-based framing bar thing (see this link, for example) that they offer, and I bet people use.  You don’t have to be a member to use it: I hit that link in a browser that allows cross-site frame loading and I get the bar and the page it’s framing, and I’ve never been a StumbleUpon member.  The source shows it’s using iframes to make it happen.  So far as I can tell, it’s not really different from the DiggBar.

So why do we have people writing JavaScript and PHP and Ged-knows-what-else that specifically busts out of the DiggBar framing, instead of busting out of all framing?  After all, site framing is universally agreed to be objectionable; even yet-to-be-discovered life forms orbiting distant stars think it’s a bad idea.  So why is one instance of it being targeted while the rest are tolerated?  Why are we all not just using if (top != self) {top.location.replace(self.location.href);} and other-language equivalents?  Yes, I know, some of you do just that, but why isn’t everyone?

Perhaps because I have yet to eradicate a stubborn streak of faith in the rationality of my peers, I assume that there’s some technical difference here that I’m missing and that, once understood, would let me understand the source of the outcry.  So can someone please explain to me, or point at an explanation that states, the technical ways in which the DiggBar is worse enough than already-extant framing bars that it’s triggered this outrage?  Again, nobody has to enumerate the complete list of the DiggBar’s sins; I understand.  A list of any different and more egregious sins would be just fine, though.

Also, if anyone comes up with a way to bust out of the frames while still preserving the bar—that is, correcting the problems framing bars cause while preserving their functionality for the people who want to use them—that would be extra-cool.  After all, people who use those services like the bars.  If we could let them browse the web the way they prefer while fixing bookmark/SEO/etc. problems framing bars can cause, that would be a win all the way around.

Update 14 Apr 09: looks like Porter‘s trying to keep the bar without the framing.

Update 16 Apr 09: in his post about Digg changing the way the DiggBar will work, John Gruber lists (by way of quoting Digg VP John Quinn’s post about it) the two things that made the DiggBar extra-objectionable (at least in his eyes).  Thanks, John!

• Digging in the Mud was published on Tuesday, April 14th, 2009.
• It was assigned to the Questions, Tech, and Web categories.
• There have been twenty-two replies.

In creating the combo-bar charts for the survey report, I stumbled into an Explorer bug that I didn’t remember ever seeing before, and Google didn’t turn up anything that seemed to be related.  This could easily mean that I’m the only person who ever did something this insane and thus found the bug.  It could just as easily mean that my Google-fu has failed.  Either way, I’ll write it up here so it can enter the collective memory.  (And surely someone has already noted that Google is positively Jungian?)

You can see both the problem and two workarounds if you visit this test page using IE6 or IE7.  In brief, the problem occurred when I had a table cell containing a paragraph with an explicit width set.  I did this through the style attribute, though tests show that for this bug, it doesn’t matter whether you use the attribute or assign it via a style sheet.  Around these explicit-width paragraphs were div elements with width: 200%;, for bar-drawing purposes (it’s a little complicated).  Everything was fine in 99% of cases.  But as soon as the header text at the beginning of the row went to two lines of text, the explicit-width paragraphs doubled in width.  What was 80.1% wide would be drawn as though it were 160.2% wide.

My hopefully understandable reaction was to say, “Whuh?”.  I threw a few hasLayout triggers at the offending paragraph (relative position, zoom, etc.) and got nowhere.  In the end I worked around the problem by telling IE6 and IE7 to not wrap text in the row headers of combo charts.  (The bug is not present in IE8.)

I mentioned all this in my announcement post, and the ever-awesome Dan Wilkinson discovered that the problem could be fixed by setting all of the table rows to, say, height: 3em.  Armed with that breakthrough, I experimented a little more and found that I could actually set the offending table row’s height to 2.75em and still have things work as intended.  Below that and the paragraph widths doubled.

Then I lowered the line-height of the headers to 1 and found that I could take the overall row’s height as low as 2.33em before triggering the bug.  And that’s when it dawned: the bug was triggered by the layout height of the header cell’s content being taller than the content of the cell containing the paragraph, and not explicitly declaring styles that would make the data cell as tall as or taller than the height needed to have the header cell contain its content.

Okay, that’s a little dense.  Let me step through the symptoms and two found workarounds to see if that clears it up:

1. The data cell always has a single line of text.  The bug is triggered by having the header cell go to two lines of text, whereas it is not if the header cell has a single line of text.
2. If the row’s height is explicitly set to a value equal to or greater than the header cell’s content, the bug is not triggered.
3. Alternatively, if the height of the data cell is set or forced to be equal to or greater than the height of the header cell, the bug is not triggered.  This can be done with an explicit height or with added top and bottom padding or by adding top and bottom margins to the paragraphs in the cell.

Some side tests I did indicate that the header cell is not needed to trigger the bug.  In other words, the problem could happen even if there are only data cells in the row.  Furthermore, I found that the width-scaling was directly affected by the width of the wrapping div, and thus the widths were doubling only because I had the div‘s width set to 200%.  If I set it to 150% instead of 200%, then the paragraphs only got half again as wide instead of doubling.  That seems to make sense until you see it in action.  When I say the paragraphs got half again as wide, I mean that instead of being 75% as wide as the div, they were 112.5% as wide as the div.  If I set the div‘s width to 200%, then they were 150% the width of the div.

So.  As I say, this bug does not affect IE8, so that’s good, and it can be worked around in IE6 and IE7, which is even better.  The problem would be if you didn’t know how tall your cells might get—in my case, I can be (reasonably) sure that the tallest a cell’s content will ever get is two lines of text, and by setting an explicit line-height on the headers I can know how tall I have to make the rows in order to avoid the bug.

Another day, another workaround!

• Handling an Explicit-Width Bug in Internet Explorer was published on Saturday, April 11th, 2009.
• It was assigned to the Browsers and CSS categories.
• There have been nine replies.

At last—at long, long last!—the results of the A List Apart Survey 2008 are available, along with the anonymized raw data we collected.

There are a great many reasons why it took so long to get this out the door.  A big part is that it’s almost entirely a volunteer effort, which means it happens in our “free time” (and there the word “free” has a couple of meanings).  I say it’s almost entirely a volunteer effort because the detailed analysis is actually done by a pair of professional statisticians, who are paid for their time and expertise.  They did a great job once more, and did it in a reasonable time frame.  It just took us a while to get them the data to analyze, and then a while longer to take their report and findings and process them into report form.

The biggest change this year is that we’re publishing the results as HTML+CSS instead of a PDF.  This greatly increased the challenge, because it was important to me that the data be presented using styled tables, not images.  That’s easy like cake if all you’re doing is putting them up as visual tables, and we certainly do that for some of the figures.  In the other cases, where we have bar charts of varying kinds, things got difficult.  I managed to devise solutions that are 99.9% effective, and I’m both proud of and frustrated by those solutions.  Proud, of course, because I managed to wring three-stack bars out of table markup; frustrated because of the markup I had to construct to make them possible.  I think this report represents more than half my lifetime usage of the style attribute, but unfortunately there’s no way (using just CSS) to say {width: content;}.

So why not use JavaScript to do that, or to just replace the tables with canvas-drawn charts?  I did consider both, but decided that I would push as far as I could with plain HTML+CSS. 

A few implementation notes:

• I used HTML 5 in order to step around some previously unrealized limitations of HTML 4—did you know tfoot has to come before tbody in HTML 4?  I didn’t.  I did not use elements like header and footer due to known problems in Firefox 2 and related browsers, which mangle pages containing those elements.  Instead, I took the same path Jon Tan recommends, and classed divs using those names for later, easier conversion.

• The tables which underlie the charts do not have summary attributes.  If a group of civic-minded individuals would like to write useful summaries, please let me know in the comments and I’ll let you know how best to submit them.  Similarly, I did my very best to make sure all the table headers had accurate scope values, but if I botched any, let me know.

• I’m aware that Opera shows horizontal scrollbars on most chapters of the report.  This is due to its refusal to apply overflow to table boxes, which according to my recent reading of the CSS 2.1 specification is the correct thing to (not) do.  Every other browser I tested does apply overflow to table boxes, though, which I found most useful.  I tried applying overflow: hidden to a few other boxes, and that got rid of Opera’s horizontal scrollbars, but it also cut off actual content in some other browsers.  I chose a cosmetic problem in one browser over loss of content in others.  The best fix I’ve devised is to wrap the tables in divs and apply overflow: hidden to those divs, but I didn’t want to rush the fix and botch it, so it didn’t make it in time for first publication.  I expect to get it in shortly after publication.

• In a like vein, there are a few combo charts where a bar goes shooting off the right side of the chart in IE7.  This appears to be due to some kind of width-doubling problem that’s only invoked on elements with a style attribute when the row header goes to two lines instead of being just one.  Googling for an explanation yielded no joy, and a lengthy series of attempts to hack around the problem came to nothing.  If anyone knows how to counteract that problem other than preventing the header text from going past a single line, I’d love to hear it.  (Update: I’ve implemented the “fix” of preventing line-wrapping in the report, so there aren’t any off-the-page bars right now, but you can see an example of the problem on this test page.)

• Surprisingly, the charts mostly work in IE6.  The exception is some of the triple-stack charts, where data points overlap when the rightmost sub-bars get too small, and also the double-width bars mentioned in the previous point.  I don’t really have a fix for this short of upgrading the browser, but if somebody finds one, I’d be happy to test it out.

On that last point, if there are questions or suggestions surrounding the implementation of the report, we can certainly discuss them here.  With regard to the survey and report itself, though—that is, the questions asked and the results we’re publishing—please direct those thoughts to the comments section of the ALA article announcing the report.  I’m hoping that we’ll have the 2009 survey up within a few months, so comments on what we asked and how we asked it, what we didn’t ask but should have, and that sort of thing could well have a direct impact on the next survey.  But please put those on the ALA site, where more people are likely to see them.

It’s done, it’s out, it’s yours—both the report and the data, about which I’ll soon write a little bit more.  Read the report, or produce your own report using the data.  Just always know that when we publish these reports, we do not mean for them to be the final word.  No, what we always mean is for them to be the first words, a starting point, a place from which to grow.  What comes next is as much up to you as anyone else, and I can’t wait to see what you do.

• Findings of the A List Apart Survey 2008 was published on Tuesday, April 7th, 2009.
• It was assigned to the Culture, Projects, and Web categories.
• There have been thirty-five replies.

One of the things that I’ve found mind-bendingly annoying about Leopard (besides its complete refusal to allow classic window management) is the “this file was downloaded from the internet, are you sure you want to open it?” dialog box.  Yes, damn it: I just downloaded the file with the express intent of opening it.  Stop bothering me.  Keep it up and I might mistake you for PC.

What’s even worse is that the dialog requires mouse input to get past.  It would be just within the limits of acceptability if the dialog buttons responded to keyboard input; if I could hit command-O or something to invoke “Open”, then I’d probably keep the safeguard in place, because I could just charge past it with a quick twitch of the fingers.  Since I can’t, I want it gone.  And of course there’s no “don’t ask me again” checkbox to tick.

After a plea on Twitter, I got pointers to a couple of ways to disable this annoyance (as well as a ton of “oh God, I hate that too; let me know if you find an answer!” replies).  The first way is done as a Folder Action.  For a variety of reasons, I’m not that thrilled by folder actions, so I gave it a pass.  The other approach is to write your own preference file.  Ah, much better!  (Why is this better?  I don’t know.  It just intuitively feel like the better approach to me.)

Now, one way is to just disable the warning for all public.item files—which is to say, every type of file.  I was tempted, but it turns out there’s a finer grain that can be applied:  listing specific file types to be ignored.  Better still!  That way I can switch this off for the file types that I download all the time, like HTML files, and keep the safeguard in place for file types I almost never download, like executable scripts.

Doing this means you need a list of OS X’s Uniform Type Identifiers, so I dug around to find that listing, which appears to have moved in the not-too-distant past.  Here’s the preference file I’ve put together with that listing as a guide.  This file lists all of the file types I don’t want to be nagged about.

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
   "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>LSRiskCategoryNeutral</key>
    <dict>
      <key>LSRiskCategoryContentTypes</key>
      <array>
        <string>public.text</string>
        <string>public.plain-text</string>
        <string>public.xml</string>
        <string>public.archive</string>
        <string>public.image</string>
        <string>public.audiovisual-content</string>
        <string>public.font</string>
      </array>
    </dict>
  </dict>
</plist>

I led with public.text because it encompasses not just regular text files, but HTML files as well; public.xml appears to cover XHTML, though I’m not 100% sure where those files fall.  public.audiovisual-content covers all audio and video files, as you might guess.  There are probably a few other types I’ll add over time, as I encounter enough resistance on certain types of files that I don’t need to be safeguarded.  I’ll probably never add public.script or public.executable to the list; personally, I prefer to be warned about that sort of stuff.

To make the magic happen, save the above file (or your own variation) as ~/Library/Preferences/com.apple.DownloadAssessment.plist.  Then log out of and back into your account.  Finito.

So if you’d like to get your Mac to be less of a nag about opening downloaded files, there’s how.  As the links above show, I’m standing on the shoulders of giants here, so my thanks to those who paved the way.  I hope that you will be able to benefit from both their work and my small additions thereto.

Update [13 Mar 09]: Potentially very bad news, folks.  I just tried this on my 10.5.6 machine and it failed utterly.  As did the Folder Action approach.  Older versions of Leopard apparently didn’t have this problem.  Anyone else seeing the same kind of thing on their machines?  If either way is still working for you under 10.5.6, can you tell us which one it is in the comments?  Thanks.

Update [18 Mar 09]: Great news, folks.  Ben Millett kindly sent me a copy of his working-under-10.5.6 file and I tried it out, and it worked!  The difference seems to be that the version I was using was encoded as “Unicode™ (UTF-8, no BOM)” whereas the encoding of the file Ben sent me is “Western (Mac OS Roman)” (both according to BBEdit).  So if your copy doesn’t work, check the file encoding.  Next I’m going to experiment with adding file extensions, and will report back if I meet with success.

• Selectively Disabling Downloaded-File Warnings in Leopard was published on Friday, March 13th, 2009.
• It was assigned to the Mac category.
• There have been twenty-seven replies.