Monthly Archives: December 2009

Brain teaser

Amongst my Christmas presents was a book, “Einstein’s riddle, paradoxes, puzzles and conundrums” by Jeremy Stangroom. One of the first puzzles in the book is this logic problem, attributed (almost certainly incorrectly) to a young Einstein:

There are 5 houses painted in 5 different colours. A person with a different nationality lives in each house. The 5 owners each drink a certain type of beverage, play a certain sport and keep a certain pet. No owners have the same pet, play the same sport or drink the same beverage.

  1. The Briton lives in the red house.
  2. The Swede keeps dogs as pets.
  3. The Dane drinks tea.
  4. The green house is immediately[1] on the left of the white house.
  5. The owner of the green house drinks coffee.
  6. The person who plays football rears birds.
  7. The owner of the yellow house plays baseball.
  8. The man living in the centre house drinks milk.
  9. The Norwegian lives in the first house.
  10. The man who plays volleyball lives next to the one who keeps cats.
  11. The man who keeps the horse lives next to the man who plays baseball.
  12. The owner who plays tennis drinks beer.
  13. The German plays hockey.
  14. The Norwegian lives next to the blue house.
  15. The man who plays volleyball has a neighbour who drinks water.

Who owns the fish?

Whatever its origins, it is a cracking puzzle. It took me the best part of an hour to solve it. If your brain is under-stimulated from Christmas TV but you are forbidden from programming, I recommend you give it a go. The answer is here (no peeking!).

Normal service will be resumed on this blog soon.

[1] See Atul’s comment below.

Free computer wallpaper

I got bored of looking at the standard Windows and Mac desktop wallpaper, so I decided to re-purpose some of the photographs I have taken on my travels. I have created standard and widescreen versions. They should be high enough resolution even for most developers’ monitors. Happy Christmas.


You can freely use these images as wallpaper on your computer. However they may not be modified, used for any other purpose or distributed (except via without my explicit written permission. I retain the copyright and all other rights to these images.


Left click on a thumbnail of the appropriate size/aspect-ratio for your monitor.

Right click on the full-size image and select:

  • FireFox: Set as desktop background
  • Internet Explorer: Set as background
  • Safari: Use image as desktop picture

1920 x 1200 wallpaper

These images are suitable for wide screen monitors (aspect ratio 8:5) including:

  • 1920 x 1200
  • 1680 x 1050
  • 1440 x 900
  • 1280 x 800

Stirling Falls, New Zealand.

Window reflection.

Peak 43, Nepal.

Palm, Queensland, Australia.

Lenticular clouds near Mount Sefton, New Zealand.

Kalahari sand at sunset, Namibia.

Heron Island, Queensland, Australia.

Waves, Hawaii.

A MiG-29 Fulcrum performing the 'cobra' manoeuvre.

Dead Vlei, Namibia.

Dead Vlei, Namibia.

Boyd Falls, New Zealand.

Great Barrier Reef, Queensland, Australia.

Great Barrier Reef, Queensland, Australia.

Aquarium, Plymouth, UK.

1600 x 1200 wallpaper

These images are suitable for standard monitors (aspect ratio 4:3) including:

  • 1600 x 1200
  • 1152 x 864
  • 1024 x 768
  • 800 x 600

Stirling Falls, New Zealand.

Window reflection.

Peak 43, Nepal.

Palm, Queensland, Australia.

Lenticular clouds near Mount Sefton, New Zealand.

Kalahari sand at sunset, Namibia

An MiG-29 Fulcrum performing the 'cobra' manoeuvre.

Boyd Falls, New Zealand.

Great Barrier Reef, Queensland, Australia.

Aquarium, Plymouth, UK.


Creating wallpaper wasn’t as easy as I thought (nothing ever is). You need images that are in landscape format, are not too saturated, contrasty or busy and are cropped and resized to exactly the right width and height. Thankfully I had some tools to help – I used PicCrop to do the cropping, BatchPhoto for batch creation of the thumbnail images, Xplorer2 for batch file renaming and Photoshop Elements for everything else. Some of the images are only available in wide screen format as they didn’t work as well in a 4:3 format.

All the photographs were taken by me with a Minolta Dynax 7D digital camera or scanned from slides taken by me with a Minolta Dynax 700si. Goodbye Minolta cameras, I miss you.

New links page

I have put together a page of categorised links to blog posts and articles that I think might be useful to developers and marketers of commercial software in general, and microISVs/indie developers in particular. I intend to add more links from time-to-time. My rules for inclusion are secret, arbitrary and capricious, so please don’t ask to have your link added.

Outsourcing software testing

Every time I write a post for this blog I carefully check it for typos. I then get my wife to proof-read it. She always finds at least one typo. Often there will be whole words missing that my brain must have interpolated when I checked it. I read what I thought I had written. She is unencumbered by such preconceptions.

Similarly, it isn’t sufficient to do all your own testing on software you wrote, no matter how hard you try. You will tend to see what you intended to program, not what you actually programmed. Furthermore your users have different experiences, assumptions, and patterns of usage to you. Even in the unlikely event that you manage 100% code coverage in your testing, those pesky users won’t execute those lines of code in the same order you did. I have spent hours testing a program without finding a bug, only to see someone else break it within minutes or even seconds.

So it is essential to involve people other than the original programmer in testing, in addition to (but not instead of) the testing programmers do on their own code. This poses something of a challenge to one-man-bands such as my own. I don’t have other programmers, let alone QA staff, to call on. I can, and do, use volunteer customers for beta testing. But, in my experience, beta testing is not an effective substitute for professional testing:

  • It is haphazard. I never hear from ~90% of my beta testers.
  • You can’t control beta testers sufficiently, for example you can’t set them tight deadlines, make them concentrate on a particular feature or do their testing on a particular operating system
  • The quality of bug reports from customers is often poor. Customers often don’t understand (or don’t have the patience) to describe a bug in enough detail for you to reproduce it.
  • Professional testers know how to break software.
  • The new release should be as polished as possible before any customers see it. Your beta testers will be some of your most enthusiastic customers. You don’t want to use up that goodwill by sending them buggy software.

Consequently I like to pay third party testers to test my own PerfectTablePlan product after I have finished my own testing and before I do any beta testing. Previously I have used, but they are no longer in business. So I decided to try a couple of other offshore testing companies I had heard about:

The problem with paying a testing company is that it is hard to assess the quality of their work until it is too late. If they report few bugs it could because there are few bugs or because they didn’t do a very good job of testing. By using 2 companies to test the same software release I was also testing the testers (I didn’t tell them this).

I paid each company to do approximately 3 days testing on the Windows and Mac versions of PerfectTablePlan. I was very pleased with the results. Both companies found a useful number of bugs in the software. They were also able to test on platforms that I didn’t have access to at the time (64 bit Windows 7 and Mac OS X 10.6). I didn’t keep an exact score, but I would say that QSG found more bugs, while TestLab2 was more responsive.

QSG found some quite obscure bugs. They were even able to tell me how to reproduce a very rare and obscure bug that I had been trying to track down for months without success. Communications were sometimes a little slow (at least partly due to us being in different time zones) but it wasn’t a huge issue. My only real grumble is their billing. Despite several reminder emails from me I am still waiting to be invoiced for the work several months later. I like to pay my bills promptly and then forget about them.

TestLab2 didn’t find quite as many bugs, but I was impressed with their responsiveness. They installed Mac OS X 10.6 within a few days of it being released, so they could test PerfectTablePlan on it. When I emailed them on  a Saturday about a last minute bug fix for Mac OS X 10.6 they tested the fix the same day. That is great service.

TestLab2 and QSG are based in Ukraine and India, respectively. At around $15/hour they are about a third the price of equivalent US/European companies I contacted (who might also outsource the work to Eastern Europe and India, for all I know). Some people believe outsourcing work to countries with lower costs of living is evil. I’m not one of them. I sell my software worldwide and I am also happy to buy my services worldwide, especially if I can get significantly better value for money by doing so. While there are rational arguments to be made about problems caused by differences in culture, language and time zone caused by outsourcing to other countries, I didn’t find any of these to be a major issue in this case. Most of the other arguments I have heard boil down to the simple ugly fact that some westerners feel they are entitled to a disproportionate share of the global pie. But I don’t see any reason why someone in Europe or North America is any more deserving of a job than someone in Ukraine or India.

With the help of these two companies I was able to put out a really solid PerfectTablePlan v4.1.0 release, despite the large number of new features. In fact, I am only just putting out a v4.1.1 with some bugs fixes several months later. I plan to use both companies again. I hope readers of this blog will give them some additional work to ensure they stay in business. But not so much that they don’t have time to do my next round of testing!

Easy screen sharing with Skype

The latest version of Skype allows you to share all or part of your screen with another Skype user in a couple of clicks.

This can be incredibly useful. So far I have used it for:

  • support – Sometimes email just doesn’t cut it. If your customer has Skype, you can use screen sharing to see exactly what your customer is doing while talking to them.
  • remote usability testingUsability testing is very important. But luring a stream of  fresh victims  to your office to take part is a logistical headache. If you use Skype screen sharing neither of you has to leave the comfort of your own computer. I have used it successully to do usability testing with people on the other side of the world.

Skype screen sharing has its limitation. The images are bit blurry, there is some latency and you can’t interact with the remote computer (as you can with services such as Copilot). But it is good enough for most purposes, and it’s free!

If you are going to be using Skype much, then I strongly recommend buying a USB headset. It is much more comfortable than holding a phone to your ear for extended periods and it keeps your hands free for typing. I use a Logitech headset and I have been quite happy with it. I sometimes get sweaty ears during a long call, but it seems a small price to pay.

Logitech ClearChat Pro USB on (affiliate link)

Logitech ClearChat Pro USB on (affiliate link)