My mother got a digital picture frame for Christmas. It's rather nice. I'm a little bit jealous. But I had to bite my tongue when I noticed one feature it shouldn't have. Occasionally, before displaying the next photo, it would overlay a large hourglass cursor - showing it was busy.

What on earth for?

If it takes longer than expected to display the next photo, it's not holding anything up; it just means the next photo will get displayed a little late. And the designers, in their wisdom, decided that the best thing to do would be to draw attention to this by sticking an ugly great big hourglass over your pictures.

They're actually telling you that while you're watching a slideshow, the device is working on a slideshow.

It's like driving your car with a little voice telling you that the engine is running every now and then.

What were they thinking?

A little while ago, Long Zheng wrote a post about one of the nice little "experience" points of Windows Vista - a feature he christened "dynamic multi-dimensional scrolling", which is just a fancy way of saying that the tree view of the folders in Windows Explorer automatically scrolls so that the majority of the view isn't whitespace (go see his post for the picture/1000 words type thing).

I like it, and I agree with Long - it's not really a feature, but it does have a good, positive image on the end user's experience with Windows. I'd like to add another: the ubiquitous use of the "sorting/filtering/grouping/stacking drop down task pane from a header in Explorer's list view". (Might not be as fancy, but it's definitely a longer name than Long's.)

XP allowed you to sort items, by date, file type, whatever. You could even group on these attributes. But it was really awkward to set; a menu option buried in a sub menu on the right click. Vista's brought it front and centre, and it's a great way to slice and dice your file views.

One of the simplest yet most effective changes is to make this functionality far more discoverable by keeping the header bar visible at all times - in XP, it was only visible in details mode (which made sorting all the harder).

The feature set it exposes is terrific. It really augments the search functionality with filtering, sorting, grouping and stacking, but that's not my favourite bit. That would be finding it in places I wasn't expecting, the most surprising of which was the add/remove programs dialog. Once you've got more than a few applications installed, that list isn't the most friendly to work with. Being able to sort, group and filter (no stacking, but it's no big loss) all of my applications is brilliant. Looking for that application you just installed that's a pile of rubbish? Just filter the "installed on" date as today.

It just makes it so easy to get at your data.

Now this is just lovely. A prototype for a (physical) desktop clock that wirelessly syncs with Google Calendar to show you your upcoming appointments.

Big deal, huh?

The difference, as ever, is in the details. It's (going to be) made by the people behind the Ambient Orb (you know, the one that's been hacked to show continuous integration build status. There, see. Now you remember). The background colour of the device changes to show that you're free, you've got 10 minutes before an event or you're in the middle of one. Nice.

But the really nice thing is the amount of information it displays on the screen without words. Two icons around the outside of the clock face show you when your work day starts and ends (e.g. 8am - 8pm). A black segment of the clock dial represents an event. And if you enter the location of the event in Google Calendar, the device will use Google Maps to work out how long it will take you to get there and display dots around the dial before the event to show when you should leave.

It's just lovely.

There's an online version, too, not that I've tried it. And there's a gallery of alternative designs to vote on, but none of them have the simplicity of the design on the homepage.

OK. Even I'll admit that this looks really petty, but let's face it - I've got a point.

Just look at this from a simple usability point of view. Nobody uses the 24 hour clock in Real Life. If I'm arranging to meet someone, it's never at "18 hundred hours" or "1815", but "6 o'clock" or "quarter past". I can tell if it's in the afternoon or not by checking to see if the sun is up (if it's 2 o'clock and dark, it's am. If it's light, pm. Easy.) I have to translate to 12 hour every time I look at it. I know it's not hard, but it's like reading in a foreign language - it gets in the way of what I'm trying to do; it makes me think about the format of the time, rather than what I'm doing, like checking to see if I'm late for an appointment.

Timetables are the only place I'm willing to concede that it's useful (and the military, well, they'll do what they want to anyway...). And then they're not doing anything that you couldn't do with "am" and "pm". In fact, I've started seeing timetables do just that, and they're much easier to read. And I don't understand why cinema's need to use the 24 hour clock either - they're not open at 8am, so you could tell just from the context what time the film starts. And using the 24 hour clock is just too formal - I only want to see a movie.

Now, I'm aware that this is just a cultural thing. A Frenchman I know used to jot down meeting times in 24 hour notation. It was natural to him - he used it. Here in the UK, we don't use it.

So, what does actually wind me up about all of this is that every video, radio, cooker, alarm clock or any other electrical item you can mention will have a 24 hour clock. These items are supposed to be labour saving, user friendly devices, and yet they don't even present the time to us in a format that we want. I'd really like to hear why a video designer chose to implement a 24 hour clock...

Even Windows gets in on the act - it's default time formatting for the UK is 24 hour. So even everyone's computer is adding to the trouble.

Petty? Perhaps. Poor usability? Oh yes. Bad design? Definitely. Know your target audience. Build appropriately.

(Or the alternative moral: if you're designing a new DVD player for the UK, please make it display the clock in 12 hour. You'll have at least one customer.)