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Does your mouse not behave as you'd expect? It's probably not the mouse itself, but Mac OS X's acceleration curve, which Apple changed from Mac OS 9 to Mac OS X - Parrish Knight explains what's going on and how to retrain your mouse to track your movements more appropriately. Also this week, Adam shares some surprising findings about Internet surveys and looks at Picnik, a Web site that provides most of iPhoto's image-editing features; Glen McAllister finds local music performances using iConcertCal; and Glenn Fleishman celebrates the expunging of the court case against security researcher Randal Schwartz. We also note the release of Parallels Desktop Build 3186 (essentially, version 2.0), a security update for QuickTime, the availability of Macworld Expo session videos and audio files, and a new estimate of the number of Mac OS X users (22 million!).

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ExtraBITS Transitions to TidBITS Publishing System

  by Adam C. Engst <>

Those of you who read our breaking news items in ExtraBITS may have noticed some changes this week. As part of the major overhaul to our back-end, something we're calling the TidBITS Publishing System, we can now make articles in our database available on our home page (and in searches) before they appear in a TidBITS issue. In the recent past, we did this by posting articles to a separate blog that wasn't connected to our searchable article database. But until we published the issue containing those articles, they wouldn't show up in searches, and after we published them, they appeared twice on our home page (once in the issue, once in ExtraBITS). It was functional, but inelegant.

We're also working on a major redesign to our Web site, but until that's complete, headlines to articles that haven't yet been mailed out in a TidBITS issue will still appear on our home page in the ExtraBITS space. I've also redirected the ExtraBITS RSS feed to our main RSS feed, which now shows articles as they appear throughout the week, rather than only after being mailed out. If you're checking the main ExtraBITS Web page regularly or receiving its articles via email, this will be its last post, and I'll eventually redirect it back to the TidBITS home page.

QuickTime 7.1.5 Patches Panther, Tiger, XP, Vista Exploits

  by Glenn Fleishman <>

Apple has released an update to QuickTime for Mac OS X 10.3.9 and later, Windows XP, and Windows Vista. QuickTime 7.1.5 fixes numerous bugs, along with a flaw that could enable a maliciously crafted file to crash a program employing QuickTime or to allow arbitrary code execution - a phrase that often means there's a potential for an attacker to gain control of a computer or, at least, install malware.

Affected file types are broad: 3GP videos, MIDI files, native QuickTime movies, images in the venerable PICT file format, and QTIF files. Apple's notes indicate that a user need only open a maliciously crafted file, which means that Web sites could be used to launch attacks by embedding QuickTime documents in the right format.

There have been no reports of this flaw being exploited in the wild. A previous QuickTime flaw related to handling of JavaScript was exploited, notably on MySpace. Apple claims to have provided a temporary fix to MySpace, but it's unclear if that fix has made it into QuickTime 7.1.5.

Parallels Desktop 2.0 Ships

  by Joe Kissell <>

Parallels has now released the official update to the Parallels Desktop virtualization software that began public beta testing at the beginning of December 2006. Confusingly, the company doesn't use normal version numbers (like "2.0," which this would be in conventional terms), but the now-available Build 3186 is the first version since Build 3036 three months ago that the company considers a full, non-beta release. (Parallels advertises the build number on the download page.)

Parallels hasn't added any major new features since we last reported on the beta version (see "Parallels Desktop Ups the Ante," 2006-12-04), but the company has enhanced and debugged the features that were added then. One of the new features I'd mentioned as being problematic in December was support for running a copy of Windows installed on a Boot Camp partition directly within Parallels; switching back and forth between the two modes of running Windows previously prompted repeated requests to reactivate Windows. Now the reactivation request should occur, at most, once.

Among the numerous other new features is Coherence, a mode in which windows from Windows applications can intermingle with those from Mac applications, and even get individual icons in the Dock; Transporter, a tool for migrating an existing installation of Windows on a PC to Parallels; USB 2.0 support; an easy-to-use Installation Assistant; and the capability to copy files and folders between Windows and Mac OS X via drag-and-drop. Graphics performance is improved, but Parallels does not yet offer 3D graphics support, meaning that for now, users must still reboot using Boot Camp to play graphics-intensive games, or use the beta version of Fusion, VMware's competing virtualization environment, which has preliminary 3D support.

The new version of Parallels Desktop is a free update for registered users, who can obtain it either using the application's Help > Check for Updates command or by downloading it manually. The installer weighs in at 58 MB and can function as a 15-day free trial for those who have not yet purchased the program. Parallels Desktop sells for $80, but readers of "Take Control of Running Windows on a Mac" receive a coupon for $10 off. The current version of that book already covers the new features in Parallels, since it was released after beta testing began.

New Interviews with Adam and Joe

  by Adam C. Engst <>

Tune in to the latest podcast interviews with TidBITS editors! At Macworld Expo, Adam talked about the show announcements with host Harris Fogel of Mac Edition Radio, and more recently, Joe spoke with Gene Steinberg of the Tech Night Owl Live (he's in the final third of the 01-Mar-07 show).

22 Million Mac OS X Users

  by Glenn Fleishman <>

We often wonder how many of us there are. While Apple occasionally shares the number of active Mac OS X users, it has been a while since the last update. Eight months ago in August 2006 at Apple's Worldwide Developers Conference, Steve Jobs said there were 19 million active Mac OS X users. Keith Bachman, an analyst at Bank of America Securities, now quotes a higher number in an AppleInsider article: 22 million users of all versions of Mac OS X. Bank of America Securities estimates an increase of 6 million Mac users since the release of Mac OS X 10.4 Tiger in June 2005. It's also highly likely that there are uncounted millions of users still using Mac OS 9 and earlier.

Macworld Expo Sessions Available for Download

  by Jeff Carlson <>

At Macworld Expo in January, I delivered a session called "Graduate from iMovie to Final Cut Pro" as part of the Users Conference track. I thought it went pretty well, especially since public speaking doesn't come naturally to me (but I'm working on it).

As I was leaving, one man asked if the presentation would be made available online (and I'm sorry I didn't get your name, so I hope you're reading this). My plan was to take my Keynote file, export it as a movie, dump it into GarageBand, and re-do the session as a voiceover that could be downloaded. Unfortunately, I haven't had time to do that, but now I don't have to.

The folks at IDG have started a new service called Macworld Encore, where you can download individual sessions as iPod-compatible QuickTime video or audio files. The sessions aren't free, but they're pretty reasonable: the Users Conference sessions (mine included) each cost $5; the all-day Power Tools Conferences cost $30; Mac IT tracks cost $7 apiece; Market Symposiums cost $15; and the Hands-on Mac Labs cost $10. (A DVD-ROM containing everything is also available for $300.)

My session includes the audio (and it seems as if they tempered the initial audio feedback we dealt with right at the beginning) plus everything that was shown onscreen.

If you attended one of the paid conferences and weren't able to sit in on a session you wanted to catch, this is an inexpensive way of getting it; and if you weren't able to make it to Macworld Expo at all, a few individual downloads are much cheaper than a trip to San Francisco would have been.

DealBITS Winners: Panergy's docXConverter Premium

  by Adam C. Engst <>

Congratulations to Paul Schreiber of and Derrick Yamaura of, whose entries were chosen randomly in last week's DealBITS drawing and who received a copy of Panergy's docXConverter Premium, worth $29.95. All entrants received a 20 percent discount on docXConverter. Thanks to the 488 people who entered this DealBITS drawing, and we hope you'll continue to participate in the future!

Security Hacker Returned to Life

  by Glenn Fleishman <>

Randal Schwartz was too curious for his own good. As a contractor at Intel in Oregon in the early 1990s, he poked and prodded a bit too much, especially in the area of demonstrating how poorly chosen - how weak - many account passwords were in the groups he worked for. Schwartz is best known as an expert in the programming language Perl that is widely used for Web applications alongside later arrival PHP. (In fact, big hunks of TidBITS are now powered by Perl.)

Most system administrators view testing passwords for strength as one of many tests to ensure that a network and its associated computers are resistant against infiltration and compromise. However, disputes in the manner by which Schwartz ran his password-cracking tests and the permission he had to do so led to him being released from Intel, charged with a computer crime under Oregon law, and convicted of three felonies. He also had to pay restitution to Intel and a large pile of legal costs - hundreds of thousands of dollars in all.

Those convictions have now been expunged, and I'm happy to spread the word. On 01-Feb-07, a court ordered that due to "the circumstances and behavior of the defendant since the date of conviction" and his completion of all provisions required of him, his conviction and arrest are to be removed from the record. In the words of the order, "the defendant...shall be deemed not to have been previously convicted or arrested."

The conviction was a travesty of justice, one that I'm not convinced would have been upheld by Oregon's Supreme Court or higher courts. The judge noted in one part of the trial that the law appeared to characterize changing the background color of a computer's operating system display as a crime. (An appeal in 2001 resulted in a mixed bag of results.) And I don't believe anyone has been prosecuted since in Oregon in a remotely similar manner.

The PDF of the expungement order can be found at the Friends of Randal Schwartz site, which has extensive archives of public statements on the matter by those involved, which make it pretty clear that Intel was running the prosecution, and that Schwartz was convicted partly on the basis of police recollection of one conversation while his home was being searched.

Schwartz never said he acted intelligently in the matter. He was read his rights by the police during a quasi-raid of his premises, and he spoke without a lawyer present. He had been asked multiple times to not run cracking software and to turn off software that allowed him remote access for various purposes. And he held off reporting the flaws he found for so long that it looked like he was hiding something.

But I have long maintained the prosecution was pretty much a farce. Schwartz had no criminal intent and the "restitution" he paid Intel was for them to fix problems that existed before he demonstrated them. In fact, Intel would have paid a huge price had criminal crackers gained access to their systems; they probably should have paid Schwartz a bonus rather than trying to get him put in the pokey.

Schwartz never served jail time. In fact, the judge in the case was remarkably sympathetic to him but had to follow existing law. But he was, until a few weeks ago, a felon, and that's a cross to bear in the post-9/11 world. As an internationally recognized program-language expert, Schwartz's ability to work on certain government and corporate contracts was restricted, and traveling outside the United States was quite difficult.

I met Schwartz through Geek Cruises's first Mac Mania cruise, a great week spent with lots of Mac writers I had long known or wanted to meet, and a fantastic set of attendees. Schwartz has been on every Geek Cruise, a sort of vocational hobby of his now, a fact I accidentally confirmed at Macworld Expo with CEO and "Captain" Neil Bauman, who runs the conference series.

On the last day of the cruise, as we waited to get called to disembark, Schwartz sat in the lounge from which we had Wi-Fi access to a slow Internet connection explaining to people how they were sending their passwords in the clear over the Wi-Fi connection - and he would tell them a snippet of their password to prove it. It was a startling wake-up call to those present, and an ironic callback to what led to his difficulties in the first place.

A few years ago, Schwartz asked me if I, along with a number of other people, would write a letter to the then-outgoing governor of Oregon asking for a pardon. In it, I described Schwartz's consistent white-hat behavior, his generosity with his time, and his strict adherence to the terms set at his sentencing. The governor declined to issue a pardon, but as I wrote at the time, Schwartz demonstrably never had any intent to cause harm, only to improve security, and erred only in violating company policies. There was never any proof - nor any needed under Oregon law, unfortunately - that Schwartz obtained any information he wasn't intended to have, either.

I'm delighted that Schwartz has been rendered unconvicted. And I wrote this article in part to spread the word, in part to note how easy it could be to be charged and convicted of a computer crime for actions that may not seem problematic at the time, and in part to file this brief with Google - so that Schwartz's name is associated more with the absence of a conviction than the presence of one.

Lessons on Internet Surveys

  by Adam C. Engst <>

We've been watching the results of our reader survey roll in, with over 2,800 responses so far. You can still vote, but I can likely predict how you'll vote, based on current responses. In fact, the percentages of certain answers have been stable since the first few hours of the survey.

This fact - that not much data is necessary to draw accurate conclusions - goes against the strongly held belief among many survey professionals that a high response rate is necessary. In fact, for a proposed survey to win a federally funded grant, one of the most important criteria is a predicted high response rate, and media pollsters performing quick surveys seldom report their response rates because they're so low. But according to Dr. Jon Krosnick of Stanford University, that belief turns out to be wrong, something that researchers are just coming to realize.

Dr. Krosnick spoke last week as part of a speaker series organized by the Cornell University Survey Research Institute, and although Tonya and I felt somewhat out of place in a room of academics, we were pleasantly surprised to find Dr. Krosnick's talk engaging and accessible even to those of us who have no formal training in surveying or statistics. If you're extremely interested in the topic, I encourage you to listen to the talk (26.6 MB MP3); for the rest of us, I thought I'd offer a quick summary of the non-intuitive lessons Dr. Krosnick imparted and a few other facts of interest to anyone who has been asked to complete a survey in person, over the telephone, or on the Internet.

  1. Telephone interviews are not good substitutes for face-to-face interviews. They've become commonplace because their lower cost - between $1.50 and $6 per minute per respondent, compared with up to $1,000 for an hour-long face-to-face interview, once you factor in hiring and training interviewers, travel time, and so on. However, when examined on a number of scales, telephone interviews turn out to be significantly less accurate than face-to-face interviews.
  2. As much as telephone interviews aren't great, mailed paper questionnaires suffer from even worse accuracy. The thought is that people tend to whip through questionnaires too quickly, thus reducing their accuracy (in one telephone versus questionnaire survey comparison that asked pilots about dangerous experiences, those pilots who completed the paper survey rated their answers as less accurate than those who were interviewed on the phone, and remembered fewer dangerous incidents). The attraction of paper surveys is that they're cheap, but it turns out that once "the Dillman method" of sending reminders and multiple copies is employed, the cost savings over telephone interviews are minimal.
  3. I've already noted the third lesson - that low response rates aren't nearly as much of a problem as previously thought. That's a good thing, because Dr. Krosnick noted that telephone survey response rates are dropping precipitously; one ongoing survey that has traditionally had high response rates is seeing them drop by a half of a percent per month.
  4. Computer-based surveys turn out to be significantly more accurate than telephone surveys, perhaps because people subconsciously consider computers to be more human than a stranger on the phone. Plus, with computer-based surveys, if questions are asked one at a time, respondents can think about their answers without having the social awkwardness of telephone silence. There's also some thought that people are more honest when not speaking directly to another person. The lesson here is that computer-based surveying over the Internet is big business already, and will only get bigger as it takes over for telephone and questionnaire surveys.
  5. The problem faced by most Internet surveys is that they seldom rely on a random sampling of respondents. Most Internet survey firms recruit users in a way that can easily lead to non-random groups providing results that are less accurate than those from a truly random sample. Apparently, there's only one Internet surveying firm employing true random sampling - a company called Knowledge Networks, and in a test of a number of Internet survey firms and a well-regarded telephone survey firm, Knowledge Networks's results were overall more accurate than any others. In fact, Knowledge Networks goes so far as to provide panelists with an MSN TV Web browser and Internet connection if necessary. In contrast, many other firms rely on people who want to earn money taking surveys, and as with so many other things on the Internet, it's easy for these people to misrepresent themselves in order to participate in more lucrative surveys. Unfortunately, properly done Internet surveys end up being roughly comparable in cost to telephone surveys, though it would seem that costs could drop.

A Novice's Conclusion -- We found Dr. Krosnick's talk utterly fascinating, and although we didn't have time to chat with him beyond the Q&A session at the end, it would seem that some conclusions could be drawn from his lessons about the kind of Internet polls and surveys we see so frequently.

First, although there is absolutely no disagreement that a random sample is ideal, the difference in accuracy was not huge. When applied to a question that is likely to have relatively divergent answers (such as the age of TidBITS readers), useful conclusions can easily be drawn without worrying that a self-selected sample would be horribly biased in one direction. Attempting to distinguish between answers separated only by a percentage point or two wouldn't be possible, though.

Second, even if the response rate isn't huge, that wouldn't seem to make much of a difference. We might end up with a response rate of less than 10 percent in our survey, but the added accuracy gained by a larger response rate certainly wouldn't be worth harassing you all multiple times to answer our questions. Just how small that rate can be isn't entirely clear, but single digits don't appear to be a major problem.

Third and finally, unlike a survey gauging national voting plans, most Internet polls don't attempt to use the results to predict the future, nor are the results likely to affect the future actions of other people. I can't quite put in words why this seems like a relevant difference, but it's related to the goal of the survey. If I learn what percentage of TidBITS readers regularly play computer games (28 percent), I can use that information when considering what articles to write, but I can't see the publication of this fact causing people either to start or stop playing games. However, compare that to surveys that ask who you plan to vote for in the next election; your answer has the power to help sway the opinions of other voters.

And in that thought is where I think the answer to decreasing response rates lies. Surveys can be intrusive and badly timed, but if it's reasonable to complete them, they should be seen as a way of spreading your opinions to the rest of the world. It's the same reason I don't mind using grocery store shopper cards; I know they're tracking my purchases, and I want the fact that I'm buying more organic and less processed food to be recorded prominently. So the next time you're polled, consider it a chance not just to be counted, but also perhaps to nudge the world in the direction you want.

iConcertCal: Your Gig-Going Pal

  by Glen McAllister <>

Until recently, I haven't been a regular visitor to Apple's Mac OS X Downloads page, but after coming across their latest featured download, I may make a point of checking more often. The program in question was a nifty iTunes plug-in called iConcertCal, which generates a personalized calendar of concert dates based on artists in your iTunes music library and your location.

After installing the plug-in and (re-)launching iTunes, iConcertCal appears as an alternative to the normal iTunes visualizer. Choose View > Visualizer > iConcertCal, and then activate the Visualizer by choosing View > Turn on Visualizer (or press Command-T). Enter your city, state (or country for those outside the United States), and a radius (in miles) from that city (it's not inherently obvious that you can type in those fields, but you can).

Once it knows your location, iConcertCal generates - within the iTunes window itself - an iCal-like calendar of concerts in venues within the area. What's truly neat is that it displays only concerts from artists already in your iTunes library. The calendar is generated by feeds from live music sites such as JamBase and is updated weekly. Clicking a concert link in the side list of upcoming shows or in the calendar itself takes you to the show's entry on JamBase. Pressing Command-T returns iTunes back to the normal view.

If you're interested in concerts by artists whose music you don't already own, you can tell iConcertCal to expand its search by putting those missing artists' names in a text file called "iConcertCalOtherBands.txt" in ~/Library/iTunes/iConcertCal (one artist per line). It's more likely that you'll have songs from artists who you'd never want to see live (imagine the free weekly downloads from the iTunes Music Store; you might like a song well enough to keep it, but not well enough to attend a concert by that artist). To restrict iConcertCal's searches, create a playlist - it can even be a smart playlist - called "iConcertCal" that contains just those artists you want to see.

iConcertCal is only as good as its data source, which sometimes disappoints. It failed to report a scheduled concert I'm keen on attending - The National at London's Astoria on 22-May-07, which is by no means a low-profile show. However, you can join JamBase and add both artists and shows and, if accepted, they will show up next time your (and everyone else's) calendar is updated for that location. Then you will have the pleasure of making an already cool thing even cooler for everyone.

[While editing Glen's article, I decided to see if adding an artist to JamBase was onerous, and I'm pleased to say that it wasn't. So hopefully JamBase will start reporting shows by my current favorite jazz group, the New York City-based Dave's True Story. -Adam]

iConcertCal is a universal binary requiring Mac OS X 10.3 or later in conjunction with the (encouraged) latest version of iTunes. There is also a Windows version. You can download the 340K installer from Mac OS X Downloads or the product's own page. It is freeware, but you can make PayPal donations on the iConcertCal site. I've already done so!

[Glen McAllister is a licensed busker on the London Underground and freelance IT consultant.]

Picnik Duplicates iPhoto on the Web

  by Adam C. Engst <>

For an impressive example of what can be done in a Web application these days, check out Picnik, an online photo site that provides - almost exactly - the same set of editing features as Apple's iPhoto, and some of iPhoto's sharing capabilities. Picnik offers, in its Edit tab, tools to auto-fix, rotate, crop, resize, adjust exposure, tweak colors, sharpen images, and remove red-eye. There's also a Creative Tools tab that provides special effects such as making a photo black-and-white or sepia, boosting color, softening the image, and applying either a matte or vignette effect. The controls are obvious and easy to use, and Picnik provides unlimited undo. You don't even have to feel constrained to the browser window; click the Picnik name in the upper left of the window to make the Picnik window full screen.

Photos can be brought in from your account on the online photo sharing site Flickr, from your computer, from any Web site, from Yahoo or Flickr searches, and even from a webcam. And when you're done editing, you can save photos to Flickr, send it to someone via email, save it to your Mac, email it to a Web site (useful for sharing to Ceiva picture frames; see "Ceiva and the Mac," 2005-02-14, for more on that), or print the photo on your own printer. I don't see any options for ordering prints from a service yet, but perhaps the assumption is that you'd do that via Flickr and their printing partner QOOP for now.

(To get Picnik working with an iSight camera, Control-click or right-click in the Picnik window, choose Settings, click the little video camera on the right side of the bottom icons, and choose either USB Video Class Video for internal iSight cameras or IIDC FireWire Video for external iSights from the pop-up menu; you may have to try choosing it several times.)

The most amusing part of Picnik? Cute little messages, like "Painting sky" or "Buttering sandwiches," appear when certain more lengthy operations are taking place. It's a nice touch.

Picnik's performance was extremely sprightly, and I didn't feel as though using Picnik within OmniWeb was problematic. It did crash OmniWeb once, but it is still in beta. Picnik recommends Mac OS X running on a Mac with a 1 GHz or faster processor; a relatively recent Web browser and Adobe Flash 9 are also required.

During its beta phase, Picnik is free, and they promise the basic editing capabilities will remain free after launch, when there will be a for-fee premium version with advanced editing, more tools, and additional features. For now, I suspect most Mac users will think iPhoto is easier and more powerful than Picnik, given that iPhoto is a full-fledged application integrated into Mac OS X. But Picnik's tight integration with Flickr may cause it to be more interesting to those who use Flickr heavily, and it's possible that being a Web-based application may enable Picnik to evolve much more quickly than iPhoto, which Apple updates approximately once per year.

Mac OS X's Mouse Acceleration Problem

  by Parrish S. Knight <>

As wonderful as Mac OS X is, it has a grave defect that can have an immediate adverse impact on the computer's usability: the way it translates mouse motion into pointer movement. For many users, moving the mouse feels unnatural because of the peculiar way that Mac OS X performs that translation. In industry parlance, the translation is called the "mouse acceleration curve." What is a mouse acceleration curve, and how is its implementation problematic under Mac OS X?

Speedy Gonzales -- Mouse movement cannot be translated into pointer movement at a simple one-to-one ratio. If it were, you'd need to move the mouse 17 inches (43 cm) across your desk to move the pointer across the diagonal of a 17-inch monitor. That would be highly impractical because you'd need a tremendous amount of space to move the mouse around, and your arm would tire quickly. (Either that, or you'd have to constantly pick the mouse up and put it back down, which would also be both tedious and wearisome, though possibly amusing to watch.)

Can you compensate by increasing the ratio so that, say, the pointer moves three inches for every inch the mouse moves? That simply trades one problem for another one. For example, on most displays, even at lower resolutions, the centers of the close and minimize buttons at the top of a standard window are typically about .25 inches (6.4 mm) apart (at higher resolutions, it's even less than that). With a three-to-one pointer-to-mouse movement ratio, then, you'd have to move your mouse about .083 inches (2.1 mm), no more, no less, to move from the center of the close button to get to the center of the minimize button. That's roughly the thickness of three credit cards. Moving a mouse with such precision is difficult for most people, and if it were regularly required, it would make the computer cumbersome to use. So a simple "X-to-one" acceleration ratio won't work because if the value of X were too low, you'd still need lots of space to move the mouse around, but if the value of X were too high, precise pointer movement would be impossible.

The solution is for the operating system to use both concepts: a higher X-to-one ratio for faster mouse movement, enabling the user to move the pointer across the screen quickly with little use of desk space, and a lower X-to-one ratio for slower mouse movement, enabling the user to move the pointer precisely without needing to be fantastically precise in moving the mouse.

With this solution in place, users get the best of both worlds. If a user is moving the mouse very slowly - say, doing detailed work touching up a photo - the mouse-to-pointer ratio might be one-to-one (or even less than one-to-one), enabling precision movement with ease. Conversely, if the user then starts to move the mouse more quickly, wanting to jump to the other side of the screen, the X-to-one ratio changes dynamically, increasing as the user continues to increase the mouse's speed, until it reaches the other end of the X-to-one ratio, which might be as much as nine- or ten-to-one. Finally, as the user instinctively starts to slow the mouse down as the pointer nears the desired target, the operating system reverses the process, gradually decreasing the ratio once more and enabling the user to place the pointer precisely at the desired spot. (The math behind all of this is quite complicated. You may never look at your mouse the same way again.) The whole process makes it possible for the user to move the pointer from the photo he's touching up in the lower left of the screen to an icon in the upper right of the screen by moving the mouse only a short distance.

If you were to take a sheet of graph paper and create a standard X-Y coordinate system - remember high school algebra? - with X representing the speed of the pointer and Y representing the speed of the mouse, and then map the ratio conversion process onto that graph, you'd end up with a sloping line, moving upward at first, and then flattening out with greater values of X. This line is called the "mouse acceleration curve."

Sharp Curves Ahead -- So what's wrong with Mac OS X's mouse acceleration curve? Simply put, it's the wrong shape. For mouse motion to feel natural (at least for most people), the curve has to start by moving upward fairly moderately, then gradually flattening out as the value of X increases. Mac OS X's, curve, however, starts off by being too steep, staying too steep for too long, and then flattening out too abruptly. In practical terms this means that, frequently, as a user tries to use the mouse to move the pointer from point A to point B, the pointer motion feels sluggish. The user then tries to compensate for the sluggishness by moving the mouse faster, and the pointer suddenly goes flying across the screen and overshoots point B. A comfortable and useful curve is actually shaped like a curve. Mac OS X's curve, however, is shaped more like a cliff.

It wasn't always this way. Under Mac OS 9 and earlier, the curve was different and provided more natural mouse behavior. Then, for some reason, Apple apparently decided to fix something that wasn't broken and changed the curve. They made no announcement of the change and, to the best of my knowledge, it does not appear anywhere in their technical documentation. (Microsoft, conversely, explains how the Windows XP mouse acceleration curve works on a publicly accessible Web page.) For this reason, most people don't know about the change and are wondering "why the mouse feels funny" because they don't understand the esoteric details of the mouse acceleration curve. (And who can blame them? It's anything but simple arithmetic!)

I was one such person myself for quite some time, experimenting with different mice and a variety of mouse pads and other surfaces, trying to figure out how I could get the mouse to "work right again." It was only after many months of Googling on a variety of search terms that I finally found out about acceleration curves and learned that Apple had quietly changed theirs. I was fortunate in that I had several years of experience with the Classic Mac OS that told me there actually was something that needed to be fixed. People who have only started using the Mac in more recent years have no such advantage.

The unnatural motion of the new curve is troublesome for many users. User "Sludge" on the MacSlash Web site, for example, complains, "I can't believe how horrible mice feel on OS X compared to XP and Linux/XFree86." Scott Moschella of opines, "[T]he mouse acceleration...makes OS X's mouse tracking feel like you're mousing through mud," referring to how the low end of the curve is too steep for too long.

Of course, not all users have this complaint. Some say they actually prefer the new pointer behavior, and some even claim they don't notice any difference. For those who do have trouble with the new curve, though, it's highly problematic - often in ways beyond just the difficulty in getting the pointer to move to the desired location.

When mouse movement feels unnatural, the user may subconsciously try to use hand and wrist muscles to compensate. At best, that's uncomfortable. At worst, it can be painful. In my own case, my wrist starts to cramp after only a moment or two. After about 20 minutes, most of my forearm is in extreme pain, and I have to stop using the mouse altogether.

Over time, users with this type of difficulty using the mouse can suffer from the permanent damage known as an RSI (repetitive stress injury). I am one such sufferer. An anonymous user on MacSlash rails about "the RSI-inducing unpredictable madness that is the Mac mouse acceleration curve." And on, user "PhotoHobo" complains, "One of my biggest annoyances with OS X is the horrible mouse acceleration. As someone who is constantly battling RSI, I find this intolerable." Web searches find a number of other users voicing similar opinions and having similar difficulties.

Realigning Your Curves -- So the problem is certainly real and immediate - at least for some of us - but can anything actually be done about it? There is no setting in Mac OS X itself to modify the acceleration curve. Sometimes, well-meaning users suggest modifying the Tracking Speed setting in the Keyboard & Mouse pane in System Preferences, but that doesn't provide a complete solution. The problem isn't speed, per se, but the acceleration curve. Changing the tracking speed does not change the shape of that curve. It just makes the whole curve smaller or larger, rather like using a telephoto lens (or a wide angle lens) to take a photograph of the same cliff from the same location.

Apple has left a void, then, in Mac OS X's settings. Fortunately, many third parties have tried to fill that void, and most do the job quite admirably. For example, several mouse manufacturers, such as Kensington, include their own mouse drivers and software that can be configured to override Mac OS X's mouse acceleration curve. The only drawback is that the software is usually specific to the hardware.

For those who already have mice that they don't wish to replace, there are other solutions, each with advantages over the others. MouseFix (freeware) is a simple program that changes some of the numbers used in Mac OS X's mouse driver in an attempt to make the curve more natural. However, it can be difficult to install for the non-technically inclined, and its presets are not customizable.

USB Overdrive ($20) is shareware with no trial period, and it offers an extensive variety of options for configuring mouse behavior, as well as the behavior of other USB devices. You can even configure it so that the mouse will behave differently depending on which application you're using. Its chief drawback, as the name implies, is that it supports only USB devices - if you use a Bluetooth mouse, you're out of luck. (The author, Alessandro Levi Montalcini, says that Bluetooth support is coming, but offers no time frame.)

SteerMouse ($20) is also shareware that offers a wide variety of customization options for mouse behavior, and unlike USB Overdrive, SteerMouse supports Bluetooth mice. Its main disadvantage is that it was designed with Apple's Mighty Mouse in mind - it does work with other mice, but support may be more limited. Also, the trial period is only 15 days, which may not be long enough to fully explore the software, because finding the most comfortable settings can take a while. I ultimately chose USB Overdrive over SteerMouse for this reason. SteerMouse expired before I became comfortable with it, whereas USB Overdrive, having no expiration date, afforded me ample opportunity to find the mouse settings that worked best for me.

Hopefully, Apple will realize that changing the mouse acceleration curve was a mistake and revert to the old one. Better yet would be to add a setting to the Keyboard & Mouse preference pane to enable the user to configure the acceleration curve as well as the speed. The likelihood of that is anyone's guess, but in the meantime, we can save our hands, our wrists, and our sanity by having a clear understanding of what the problem is and working around it with third-party solutions.

Mac OS X, as we all know, is the Ferrari of operating systems. Unfortunately, the steering has a design defect, but with a little mechanical effort, we can modify it while we're waiting and hoping for the engineers to recognize the problem and fix it.

[Parrish S. Knight is a systems administrator for an IT consulting firm in the greater DC area. His interests include politics, film, fantasy, and science fiction. In addition to getting the word out about Mac OS X's mouse problems, his causes include activism in autistic advocacy and civil liberties.]

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