Beware of Dark Patterns!

Dark patterns are increasingly-common user interface elements designed to trick unsuspecting users into selecting an undesirable option, such as installing an unwanted app or signing up to an unwanted service.

Although designers go out of their way to provide a sleek user interface for hooking you in, you may not always find an equivalent feature that lets you undo your mistake afterwards.

A typical example

The following screenshot comes from an installer stub program which the user must run in order to install video editor software downloaded from a popular website:

Most software will require you to accept a license agreement before you are allowed to install. In the above screenshot, the user will probably assume that the green 'accept' button is the only way to go forward with installation.

Reading the screen more carefully reveals that it is actually referring to a different, completely unrelated program; one that alters the user's web browser settings in order to display advertisements. In this case, the correct way to proceed with installing the video editor, without the unwanted extra software, is actually to click the greyed-out 'decline' button.

By accepted user-interface convention (as specified by Microsoft and Apple, among others), a greyed-out button denotes an invalid option that is not able to be selected by the user. Here however, the 'decline' button is a perfectly valid option even though it has been given the cosmetic appearance of a greyed-out button. It has been greyed out purely to deter the user from clicking on it, even though it is probably the preferred option for the majority of savvy users.

Why do dark patterns exist?

Organisations typically have a financial incentive to persuade users to install a particular program or buy a particular service. In the above case, an organisation would receive a commission for each user who clicks the 'accept' button. There are always incentives for a company to improve sales, and deceptive sales tactics are hardly anything new.

Why does it matter?

If you own a computer, you have the right to be in informed control over what runs on it.

Unwanted applications are a security risk. If you have sensitive data on your computer, you probably don't want to allow strange applications to install themselves and assume free-reign over your files.

Unwanted applications deprive you of full use of the computer you paid for. If you perform computationally-intensive tasks, you probably don't want to have your system's performance and reliability compromised by a poorly-coded application you didn't realise you'd installed.

Finally, in an age of email-viruses spread through a combination of shady social-engineering tactics and uninformed users, it really isn't a good look when otherwise-reputable organisations engage in the same tactics.

What to do about dark patterns

Ideally, you should never trust someone with your business, or your web traffic, if they do not treat you – or your computer – with respect.

If you stumble across a dark pattern on a website you're using (for example, a website that tries to trick you into adding unwanted items to your order, or one that doesn't tell you what the 'catch' is until you've already invested time in filling out your details), stop using that website and find an alternative.

If you find a dark pattern in an app you've downloaded, immediately delete the app from your computer. If the app is distributed by a reputable organisation, consider sending an email to the distributor to let them know what is going on.

More information

There's an excellent guide to dark patterns, along with a collection of examples, over at darkpatterns.org.

Getting a CNC mill

We've just got hold of a cheap CNC milling machine, which ought to come in handy when building hardware prototypes.

What's a CNC mill?

Everyone's heard of 3D printers. A CNC mill is a bit like a 3D printer in reverse. Instead of building up an object by adding material in layers, a CNC mill starts out with a solid piece of material (a block of wood, aluminium, etc.), and carves away unwanted material until you're left with the finished part. The quality is higher than 3D printing. When Apple sells a high-end product that was 'carved from a single piece of aluminium', they're talking about CNC milling.

Unlike 3D printers, CNC milling machines haven't started to become 'consumerised' yet. You pretty much have to know the machine inside out in order to use it. Fortunately, they aren't particularly complicated machines, and we do appreciate the fundamental simplicity. There are two main bits to understand:

• A spindle holds an engraving bit. It spins the engraving bit at high speed (like a drill) to carve out material.
• The spindle can be moved around in three dimensions (X, Y, Z axes) to different co-ordinates by a program script (called G-code) running on a connected PC. When you move the move the spinning engraving bit through a path where a piece of wood happens to be, wood is carved out by the spindle (unless you go too deep too quickly, or forget to spin up the spindle first, in which case you're likely to stall the machine or break something).
  The machine has a set of three motors, one for each axis of motion. Each motor turns a long screw that moves the spindle along its respective axis.

What did we go with?

We went with a YOOCNC 3020 machine. This machine is sold on eBay under a variety of brand names (just search for CNC 3020), and is just about as cheap as you can get a new machine without building your own from scratch. By all accounts, it's a machine loved by amateurs, hated by professionals, and requires the odd few modifications to overcome the inevitable design flaws. We're new to all this, so we haven't been spoiled enough to demand anything better.

Setting up the machine

The CNC machine is controlled by a PC through the parallel port interface that many motherboards no longer include (although there are cheap PCI cards available on eBay that will add a parallel port to any motherboard). The PC must provide the correct impulses in real-time, or else the CNC machine stutters or the PC application that controls it gets out of sync with the machine's actual position. That usually means that you set aside a PC that's dedicated exclusively to CNC work and nothing else.

There's a special Ubuntu-based operating system called LinuxCNC (formerly known as EMC2), which provides software for controlling a CNC machine and uses a customised Linux kernel optimised for the real-time demands of CNC machines.

For controlling the machine, I put together a PC with a 1.5GHz Via C7-D processor, 1GB of RAM, and an old 4.3GB Quantum Bigfoot hard drive that cost around $900 in 1996. I used an older version of LinuxCNC/EMC2 because the new version is based on a more bloated version of Ubuntu). The Via C7 line of CPUs came out a few years ago as a competitor to the Intel Atom. Despite mediocre performance in many desktop and gaming applications, they provide great real-time characteristics which made them well-suited to industrial applications.

Limitations of the machine

On this particular machine, the spindle control is all-manual. You have to flick a switch to turn it on, and slowly rotate a variable control to take it up to full speed. (More expensive machines allow the spindle rotation to be controlled by the computer.) The machine comes with a sticker attached warning you that you'll blow one of the internal fuses if you spin it up too fast:

The emergency stop button on the front panel is purely a software input to the PC through one of the parallel port pins, so if you have it set up correctly, it'll instruct the PC to stop moving the machine along the X, Y, Z axes, but it won't cut the power to the rotating spindle. (Looking inside the controller box though, there is an unused pin header on the power supply board for an emergency stop input for the spindle. Perhaps with a bit of work, the controller box could be modified to incorporate the spindle into the emergency stop.)

A problem we noticed fairly early on is that some engraving dust tends to get sucked into the controller box by the inbuilt cooling fan. We'll discuss this later in another blog post.

Another issue is that there are no limit switches or inputs on the controller box. What does this mean? Well, a CNC machine always knows how to move, say, 52.4mm along the X axis from its current position, but it has no way of knowing its absolute position, or how close it is to slamming into the end of its range of motion and stalling one of the motors (or, in the case of this machine, pinching the Z axis motor cable). Without limit switches, you have to zero (or 'touch-off') the spindle position relative to your work-piece each time you use it. With limit switches, the PC software can automatically home the machine to a default position each time you use it, and automatically ensure that the spindle doesn't go outside an allowed safe range of motion.

The good news is, it is possible to add limit switches to this particular machine: the PCB inside the controller box provides the capability, although there's a bit of soldering required. We'll cover this in another blog post later.

Finally, the documentation leaves a bit to be desired. Parameters are provided for a Windows program called Mach3, but EMC2 requires a few extra parameters. We found we had to start with what was given and work backwards to determine the rest.

How do you change your car's oil when you can't get the oil filter loose?

Here's something a bit different: cars. And oil changes. Cars are a ubiquitous example of the way various industries simplify their products for end users, not by making them fundamentally simpler, but by hiding complexity from the end user. Which is fine; until you have to change your oil.

You would have thought that car makers would have streamlined the oil-change process for end-users by now (where's the flap on the side of your car that lets you drain your old oil easily?). But on the contrary, the engine compartment of a new car is less accessible than that of a 27 year old car. I'm thankful that my car is 27 years old. But changing my oil for the first time still wasn't easy.

The mechanic who serviced my car last, used a rattle-gun to over-tighten everything as much as possible. Even parts like the oil filter that are only ever meant to be hand-tight. Rather than ranting about it further, I'd like to share a few tricks I came up with for getting stuck parts loose:

How to get your old oil filter loose

My oil filter wrench (the type with a metal band that tightens around the filter when you bend the handle) wasn't giving me enough grip, and at any rate, I didn't have room to swing it around far enough to make any progress. I didn't want to resort to the messy technique of hammering a screwdriver into it. Here's what I tried:

Give your filter wrench a sandpaper-surface

You can apply a coat of superglue to the inside surface of your filter wrench's metal band, then immediately sprinkle sand over the glue. When the glue dries you'll have a durable rough surface with plenty of grip (superglue isn't terribly flexible so leave gaps). Or you can simply glue strips of sandpaper to the inside of the wrench.

In my case, although the sandpaper seemed to help a bit, I still didn't have enough room to get my filter wrench tight enough around the filter.

Wedge a flat-head screwdriver between the wrench and the oil filter

Insert your flat-head screwdriver between your filter wrench's metal band and the filter. That way, when you bend the wrench handle to tighten the band, the screwdriver not only helps to take up the slack, it helps provide a concentrated point of pressure between the wrench and the band, giving you a lot of extra friction. In my case, it made all the difference, and the filter began to turn.

How to get the oil drain bolt loose on the bottom of your engine

My mechanic had put on the drain bolt on the engine sump impossibly tight. Too tight for brute force, even with a decent wrench.

• First of all, you need a decent wrench, like a hex wrench (rather than a crescent wrench or spanner) that isn't going to slip off the bolt at every opportunity. The wrench needs to have a hole at the end of the handle.
• You also need a ratchet tie-down strap. hook one end into the end of your wrench (or thread the strap through the hole until the hook stops it pulling through any further). Hook the other end to a solid part of your car's frame (if you can flex it by hand, it's not strong enough), so that when you tighten the ratchet, it will pull the wrench anti-clockwise.
• Don't use an elastic strap under any circumstances. It won't withstand the tension you're about to subject it to, and when it snaps, it could do you a very serious injury.
• Gradually tighten the ratchet. (As a precaution, just reach under the car with your arm when you do this, keeping your face and as much of your body as possible out of the way just in case something flies loose.) When the strap has enough tension, the wrench should very slowly and gradually begin to turn.

Other tips

• If your oil filter and drain bolt are readily accessible, see how tight they are before you do your oil change. There's nothing worse than having your engine warm and everything ready to go only to realise that you can't get anything loose. If they're really tight, loosen them a quarter turn beforehand (don't worry, they'll still be tight enough to prevent any leaks).
• Don't jack your car up if you can avoid it (it's safer not to). If you have your own driveway, chances are you have an inclined ramp between your driveway and the street. Back your car into your driveway just far enough so that your front wheels are at the highest point of the ramp, and the front end of the car is hanging over it. The slope of the ramp should give you a bit of clearance so that you won't have to jack your car up. (I picked up this trick from a professional mechanic.)
• I like to disconnect the negative terminal of my battery, and pull out the distributor leads from my spark plugs, before I do any work on the car (as well as making sure the handbrake is on firmly!), just to be absolutely safe.  This will also prevent other people who have access to your car from unknowingly starting the car when there's no oil in it!
• Wrap your oil drain pan in at least two layers of big plastic bags. Then wrap tape around the contours of the pan's spout so you can still pour the oil out of the pan easily. You won't have to clean the pan when you're finished.

Wi-Fi printers. Why?

Are you in the market for a new printer? If you have more than one computer, chances are you'll want a network printer rather than a simple USB printer. A network printer can be placed in a central location, and isn't tied to one particular computer.

The printer market seems to be improving now, but a year ago you would face an odd dilemma: many network printers lacked wired ethernet ports. They were mostly Wi-Fi only! What's the advantage of wireless over wired in a printer? A printer isn't something you carry with you from room to room. A printer needs to be plugged in to a power outlet, as well as a phone line if it has a fax capability, which means you'll keep it in a fixed location, such as a study; right where you have your broadband router.


There is one situation where Wi-Fi might be a useful feature in a printer: if your home/building isn't wired for ethernet, and you wish to place your printer in a different room to where you have your router. But most people do have their routers in a central enough location, and people aren't exactly un-used to having their printer placement limited by a 1.6m USB cable anyway, so this is hardly the norm.


On the other hand, there are significant disadvantages to relying on Wi-Fi for your printer. It makes the printer more expensive. It's more fiddly to set up than simply plugging a printer into a network with a physical cable. And, in the middle of a tricky situation, you may find that your printer's wireless connection is less than dependable. For most people, a Wi-Fi connection for a printer will turn out to be more a burden than a blessing.

Perhaps this is an instance of marketing gimmicks over practicality. 'Wi-Fi' sound like advanced cutting-edge technology, and rolls of a salesman's tongue a lot more smoothly than 'wired ethernet,' which, while fast and dependable, has already been around for decades.

Now available: GD-CMS version 2

We've just put out a new version of our ultra-lightweight web content management system.

Version 1 of GD-CMS was conspicuous for the lack of any kind of access through a web-based management interface, and version 2 is no different in this regard: you tweak your website by creating and editing files directly on your web host's server. (Your hosting provider already provides you with authorised file access to your webspace, so why reinvent the wheel?)

Here are the new features you get:

• The ability to have custom error pages, and even different error messages in different site categories
• Auth flags: The ability to set flags in order to control access to specific content, or provide alternative content under particular circumstances, such as for a mobile edition of your website, or when your site goes down for maintenance.
• Cascading templates: These give you the ability to override almost anything about your website (menu layout, title formatting, anything...), but only within a particular subcategory and its descendants. This allows you to have 'microsites' with unique layouts within the same content tree, themed page categories, you name it.

It's still completely free. It's grown to 15KB and could do with some optimisation, but as far as we're concerned, it's still the bloat-free web content manager. If you're developing a website, be sure to try it out.

The growing problem of light pollution

There's a type of environmental pollution that doesn't get much press. Light pollution. It doesn't affect our climate, but it does affect our ability to be inspired as human beings.

If you live in a medium to large city, here's a simple test to see if you're suffering from the effects of light pollution. Wait for a perfectly clear night, during a new moon (i.e. when the moon isn't there during the night time). Give your eyes a few moments to adjust to the darkness, then look straight up. If your jaw doesn't drop from the sheer impossibility of quantifying everything you see above you, your city is probably suffering from the effects of light pollution.

The problem is an ever-increasing number of city lights, illuminating the atmosphere and drowning out the stars. Fifty years ago, people looked into the night sky and were captivated by the scale of the universe, and the thought of a new frontier to explore. Today, people look into the night sky and see a dozen pinpricks of light against an ugly background glow.

What you can do

• If your home or business has outside lighting, make sure the lights get turned off some time before midnight (leaving them on late at night is a waste of energy anyway. There's nobody around to admire your lights).
• For security lighting, install a passive-infrared (PIR) sensor to leave the lights off until movement is detected. (These are relatively cheap nowdays, and will save you money.)
• For lights that are off the ground (such as porch lighting), use light fittings or globes that direct light in a downward cone, not in all directions. Light that goes straight out horizontally or diagonally up is wasted light that only contributes to light pollution.
• Use warm lamp colours, the warmer (redder) the better. The added advantage is that warm colours like yellow don't attract mosquitoes like cooler (pure white or slightly bluish) light does. Consider switching to warm LED globes. These use very little power (around 5W), are free of toxic mercury, and will save you money in running costs. (Although some retailers charge a fortune for LED globes, they can be purchased for around $3.50 each on eBay.)
• If you have in-ground lights, the type that direct an (often invisible) beam of light straight up into the air, save them for foggy nights (the only time they really look impressive), or turn them off after dusk.

The importance of generality in good software design.

'You should absolutely not dismiss simplicity for something easy. It takes design and good taste to be simple.'

Linus Torvalds, Just for Fun

Nobody sets out to create a really complicated software application. It happens naturally. You build a simple app that does exactly what you want it to, but then you realise it needs to do more (perhaps your competitor is pitching a specific feature, and you want to offer it too). Maybe the extra features don't quite fit in with the paradigm you wrote the original version for, or maybe the original vision has been lost. Either way, you want to extend the program's functionality as quickly and with as little work as possible. You're not trying to do anything complicated, but somewhere along the way your application turns into spaghetti.

The solution is not to build your program around special-case features, but general capability. If there's a need for a specific feature, don't build that feature specifically, generalise it to some broader class of capability. Just implement that general capability and not only do you get the functionality your users were looking for, you get added flexibility. Your users may find themselves able to do things in ways that neither you or your competitors have thought of yet. While your competitors are pitching gimmicks and saying things like 'only our software has OneClick-BusinessLetter™ and SuperBackspace™,' your design simply negates the need for those features to exist.

(Actually, a lot of the time that organisations come out with gimmicky features like this, it's them trying to mitigate some design oversight in their products, in order to keep up with a competitor's product claims.)

There's another advantage to keeping your design general. Fundamental simplicity. Design simplicity and flexibility go hand in hand; aim for one and you may well get the other. A lot of products out there are marketed as 'simple,' but they're really talking about inflexible gimmicks they've added to make their complex products appear more attractive.

It looks like you're writing a letter. Would you like help?

Clippit, MS Office Assistant, on the uselessness of gimmicky features.

There are drawbacks to taking a general, holistic design approach. It's harder. You often have to rework large chunks of your original design several times until you get it right (at least you end up with something small and manageable, in case you ever need to change it again!). The other drawback is that users tend not to appreciate good design. A good design is one that keeps out of the user's way. The problem is that it's hard to appreciate something that's designed to be invisible.

What's the solution to public perception? You can always make up buzzwords for the kinds of functionality your design provides by accident. Some companies do that. Another is the Apple approach, make simplicity a selling point. It's a shame that the word 'simple' has become a marketing euphemism for inclusion of gimmicky extras in products. True simplicity comes from keeping things general, and generality gives users power and flexibility.