more on disappearing scrollbars

I recently wrote about problems with a slightly too smart scroll bar, and Google periodically change something in Gmail which means you have to horizontally scroll the page to get hook of the vertical scroll bar.

I just came across another beautiful (read terrible) example today.

I was looking at the “Learning Curve“, a bogspot blog, so presumably using a blogspot theme option.  On the right hand side was funky pull-out navigation (below left), but unfortunately, look what it does to the scroll bar (below right)!


This is an example of the ‘inaccessible scrollbar’ that I mention in “CSS considered harmful“, and I explain there the reason it arises.

The amazing thing is that this fails equally across all (MacOS) browsers: Safari, Firefox, Chrome, yet must be a standard blogspot feature.

One last vignette: as I looked at the above screen shots I realised that in fact there is a 1 pixel part of the scroll handle still visible to the left of the pull-out navigation.  I went back to the web page and tried to select it … unfortunately, I guess to make a larger and easier to select the ‘hot area’, as you move your mouse towards the scroll bar, the pull-out pops out … so that the one pixel of scrollbar tantalises, but is unselectable 🙁

Action Research in HCI

Recently Daniel Tetteroo asked if I knew about publications in HCI, prompted partly by the fact that I have described my Wales walk next year as a form of action research.

I realised that all my associations with the term were in information science rather than HCI, and other non-computer disciplines such as education and medicine. I also realised that the “don’t design for yourself” guidance, which was originally about taking a user-centred rather than technologist-centred approach, makes action research ideologically inimical to many.

I posted a question to Twitter, Facebook and the exec mailing list of Interaction yesterday and got a wonderful set of responses.

Here are some of the pointers in the replies (and no, I have not read them all overnight!):

Many thanks to the following for responses, suggestions and comments: Michael Massimi, Nathan Matias, Charlie DeTar, Gilbert Cockton, Russell Beale, David England, Dianne Murray, Jon Rogers, Ramesh Ramloll, Maria Wolters, Alan Chamberlain, Beki Grinter, Susan Dray, Daniel Cunliffe, and any others if I have missed you!

details matter: infinite scrolling and feature interaction

Many sites now dynamically add content to a page as you scroll down; this includes both Facebook and Twitter feeds, which add content as you get near the bottom.  In many ways this is a good thing, if users have to click to get to another page, they often never bother1.  However there can be unfortunate side effects … sometimes making sites un-navigable on certain devices.  There are particular problems on MacOS, due to the removal of scrollbar arrows, a usability disaster anyway, but confounded by feature interactions with other effects.

A recent example was when I visited the SimoleonSense blog in order to find an article corresponding to an image about human sensory illusions.  The image had been shared in Facebook, and I found, when I tried to search for it, also widely pinned in Pinterst, but the Facebook shares only linked back to the image url and Pinterst to the overall site (why some artists hate Pintrest).  However, I wanted to find the actual post on the site that mentioned the image.

Happily, the image url,, made it clear that it was a WordPress blog and the image had been uploaded in February 2009, so I edited the url to and started to browse.  The site is a basically a weekly digest and so the page returned was already long.  I must have missed it on my first scan down, so I hit the bottom of the page, it dynamically added more content, and I continued to scroll.  Before long the scrollbar handle looked very small, and the page very big and every time I tried to scroll up and down the page appeared to go crazy, randomly scrolling anywhere, but not where I wanted.

It took me a while to realise that the problem was that the scrollbar had been ‘enhanced’ by the website (using the WordPress infinite scroll plugin), which not only added infinite scrolling, but also ‘smart scrolling’, where a click on the scrollbar makes an animated jump to that location on the scrollbar.  Now many early scrollbars worked in this way, and the ‘smart scroll’ options is inspired by the fact that Apple rediscovered this in iOS for touch screen interaction.  The method gives rapid interaction, especially if the scrollbar is augmented by ‘tips’ on the scrollbar (see the jQuery smartscroll demo page).

Unfortunately, this is different from the Mac normal behaviour when you click above or below the handle on a scrollbar, which effectively does screen up/down.  So, I was trying to navigate up/down the web page a screen at a time to find the relevant post, and not caring where I clicked above the scroll handle, hence the apparently random movements.

This was compounded by two things.  The first is a slight bug in the scrolling extension which means that sometimes it doesn’t notice your mouse release and starts scrolling the page as you move your mouse around.  This is a bug I’ve seen in scrolling systems for many years, not taking into account all the combinations of mouse down/up, enter/leave region etc., and is present even in Google maps.

The second compounding factor is that since MacOS got rid of the scrollbar arrows (why? Why? WHY?!!), this is now the only way to reliably do small up/down movements if you don’t have a scroll wheel mouse or similar.

Now, in fact, my Air has a trackpad and I think Apple assumes you will use this for scrolling, but I have single-finger ‘Tap to click’ turned off to prevent accidental selections, and (I assume due to a persistent bug) this turns off the two finger scrolling gesture as well (even though it is shown as on in the preferences), so no scrolling from the touchpad.

Since near the beginning of my career I have been fascinated by these fine design decisions and have written previously about scrollbars, buttons, etc.  They are often overlooked as they form part of the backdrop to more significant applications and information.  However, the very fact that they are the persistent backdrop of interaction makes their fluid usability crucial, like the many mundane services, buses, rubbish collection, etc., that make cities work, but are often unseen and unnoticed until they fail.

Also note that this failure was not due to any single feature or bug, but the way these work together what the telephony industry originally named ‘feature interaction‘, but common across all technological systems  There is no easy fix, apart from (i) thinking of all possible scenarios (reach for your formal methods in HCI!) and (ii) testing across different devices.  And certainly (Apple please listen!) if it ain’t broke, don’t fix it.

Happily, I did manage to find the post in the end (I forget how, maybe random clicking) and it is “5 Ways To Hack Your Brain“.  The individual post page has no dynamic additions, so is only two screens big on my display (phew), but still scrolled all over the place as I tried to select the page title to paste above!

  1. To my mind, early web guidance, was always wrong about this as it usually suggested making pages fit a screen to improve download speed, whereas my feeling, when using a slow connection, was it was usually better to wait a little longer for one big screen (you were going to have to wait anyway!) and then be able to scroll up and down quickly.[back]

get fit on Tiree

Today is the winter 10K run on Tiree.  It has been organised by Craig Watson, one of the airport firefighters on Tiree, in aid of the “Michelle Henderson Cervical Cancer Trust”.  It is looking a lovely day for it, although there will be a chill in the air under the clear blue winter skies.  I saw the plane land earlier and I know there are folks coming over both on the plane and the ferry to take part.  Personally I have trained with my usual level of foresight doing my first run for 6 months last Tuesday :-/

Of course this is not the only event of its kind on Tiree there is the annual 10k, which I sadly missed this year as I pulled my Achilles tendon :-(, a round island sponsored cycle in March this year, and ‘Team Tiree‘ get off island for various events through the year.

Although this winter 10K is organised by Craig, many of the island fitness activities are due to Will, runner of ironman races and organiser of the Costa del Muscle training week I took part in in August and other regular island fitness activities (from 9 to 90s!).

Next year Will is branching out and organising residential training camps, one in Majorca (for the warm weather wimps) and one in Tiree next March. The latter starts the week after the next Tiree Tech Wave, so you could come for a weekend of sitting around hacking technology followed by another of shedding flab and toning muscle!