unity-design team mailing list archive

[Luke Morton <luke.morton@xxxxxxxxxxxxxxxx>]

I like this idea. Double-clicking is an unnecessary gesture since we
have multiple buttons (or "Simulated Secondary Click" in the
Accessibilty tab of the Mouse Preferences). It confuses novice users and
is an accessibility issue for motor impaired users.

Both these sets of users would benefit from a default single-click
approach, and any user that's had enough exposure to have developed a
double-clicking habit should be able to revert the behaviour--provided
we make the preference easily discoverable by putting it somewhere
logical like in the Mouse Preferences. Unfortunately, this assumption
doesn't seem to be supported by evidence:
http://www.viralata.net/kde_usability/001_02.html (search for "double")

> To implement single clicks solves no problem and creates a whole list
> of new ones.

Single click to activate is already implemented (except in the
GtkFileChooser). As for the problem:

Ronald is 79 and his health is deteriorating. Most recently he's started
to lose his fine motor skills. This has become a particular problem for
him when using his computer. He has trouble opening files and
folders--sometimes his clicks are too slow, other times his hands shake
and the second click misses its target.

The problem of confusion has been mitigated to some extent by designing
around unwanted double-clicks. For example, launchers in the panel will
respond to a double click as a single click to avoid opening two
application instances. Nevertheless, the fact that workarounds like this
exist is evidence of a problem.

>         > You are completely right, there is a semantic difference.
>         But I wonder
>         > if (have hard times believing) that this is recognizable by
>         or even
>         > relevant to users.

The semantic difference is artificial. It's part of the model many
experienced users construct to be able to determine which operation to
apply in a given context. It's not inherent, and novice users or users
who haven't developed such a model typically struggle with
double-clicking. (That is, when to double-click and when not to.)

>         In my opinion, this is recognizable whenever the user does to
>         files
>         or folders something he does not do to launchers, like
>         deleting or
>         dragging. I personally believe your points are valid in a
>         context
>         where non-opening actions are very, very rare, and I don't
>         think
>         this is the case. People rename and delete things all the
>         time.

It's not universally recognised:
http://en.wikipedia.org/wiki/Double-click (search for "difficulties")
http://www.useit.com/alertbox/9710b.html (search for "double-click")
http://www.asktog.com/Bughouse/bhPandemic.html (search for "double")

>         > > Plus, single-click for opening would make dragging less
>         intuitive.
>         > > Firefox allows dragging of hyperlinked things, but I
>         always hesitate
>         > > before dragging an hyperlinked element, wondering if I'll
>         be able
>         > > to drag it without activating the link.

I don't know that it makes it less intuitive, but it does change the
interaction process slightly.

>         It's not like it *can't* be handled. For better or for worse,
>         Firefox does it. But I think it would hurt discoverability
>         of dragging.> Ok, don’t know how that would be handled, valid
>         and very good point.

Why? How is selecting an item first, then initiating a drag more
discoverable that simply dragging it? To my mind they're both as hard to
discover as each other.

>         > Valid and true as well; but same thing as above, especially:
>         > »launchers […] are buttons […] do some
>         > > action, whereas icons represent […] "physical" objects.«
>         > Launchers are icons, that is the problem. Do users see a
>         difference?
>         > Has it come up in usability tests?

It has, and I presume that's why the option exists in Nautilus.

As a final thing to consider: if no-one ever told you to double-click,
how would you know to do so?

Luke.