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CHI-WEB  July 2002, Week 3

CHI-WEB July 2002, Week 3

Subject:

Summary: Usability Problems and Solutions with Tree-Based Naviga tion Menus (Longish)

From:

"Bollaert, Jodi" <[log in to unmask]>

Reply-To:

Bollaert, Jodi

Date:

Thu, 18 Jul 2002 08:04:08 -0400

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (247 lines)

Greetings CHI...

A few weeks ago I posted a plea for information, lessons learned, etc. from
folks who have used tree-based navigation menus.  I didn't get a great deal
of response from the list, except for a few VERY informative notes from Matt
Prather at Bulcmale.com.  (Thanks Matt!)  Here's some excerpts from our
email exchange:

Hi, Jodi ---

These are very similar to the menu trees constructed by Web-based
Help-system authoring tools such as RoboHelp and ForeHelp (FH is now
defunct), so the usability problems I've seen in these Help systems probably
apply here as well:

*  The overriding concern is the tiny size of the clickable "twistie" or
plus-minus sign. In some case, this is the only means of
expanding/collapsing the node, and the icons tend to be tiny. In usability
tests, it was very difficult for some users to hit this target, and they
expressed quite some frustration because of it.

*  They're almost always used in conjunction with frames (the tree occupies
its own frame, usually on the left), but the frame architecture is usually
not handled very well, resulting in the well-known problems of breaking the
Back and Forward button. This also leads to a couple of other
frequently-seen problems:

--Because the tree is its own frame (and series of pages), it
often ends up being separately updated from the content it links to ---
sometimes there are even entirely separate TEAMS doing the updating! This
often results in navigation that is "out of sync" with the content: the
navigation tree says one thing, while the content page may be completely
unrelated to the navigation link.

--For the same reason, it can lead to lots of broken links that
can be very tough to chase down.

*  The systems I've used or seen most often have been built in Java and/or
DHTML, and have just been a **NIGHTMARE** for cross-platform compatibility.
In one infamous case, in the early days of the iMac, Internet Explorer was
shipped as the default browser, but the Java VM included in that browser was
*NOT* compatible with anything else on the machine (including my app). So,
users had to download a new Macintosh Java VM to use the app, but that
*still* didn't take care of it, since the browser selected the wrong Java VM
by default. It was just a huge headache and it made my company and me come
off looking very bad --- it wasn't the fault of our application, but it
APPEARED that way to users!

Recommendations: If you're going to construct this sort of navigation tool,
use an authoring system that's designed to build it and track the linkage.
This greatly reduces the number of errors. Use custom icons for the
"twisties" (expand/collapse icons) so that the clickable target can be
fairly large --- but make sure that they're readily identifiable as meaning
"expand" and "collapse". Look for an authoring tool that will accommodate
"visited link" indications; some tools don't support this. Try to avoid a
Java-based implementation; Java can be unbelievably slow and it is not the
universal solution it promised to be (it's also considered to be obsolete in
some circles...).

As a follow-up to Matt's first note, I sent a few more questions.  Here is
Matt's helpful response.

> Hi Matt,
>
> Thanks so much for your insight.  I have just a few follow-up questions if
> you have a few more minutes.
>
> - Do tree-based navigation menus necessarily HAVE to be used with frames?
> What are some of the downfalls of not using frames?

No, I don't think they really have to be used with frames. In fact, in some
earlier iterations of my own Web site (www.bulcmale.com), I used to create a
tree-based navigation scheme that did **NOT** use frames. It worked well ---
better than the current version, in fact --- but I eventually replaced it
with a "Cap'n Whizbang" Flash-based scheme simply because that seems to be a
magic buzzword that companies look for these days. Once that trend shakes
itself out a bit, maybe I can go back to something that actually works
better. Anyway, that's another story. W/r/t advantages & disadvantages of
frames:

(PRO) Using frames makes maintenance **much** easier, at least potentially.
The "potentially" may be the keyword here, though, because as I noted
earlier, there's a big cognitive load of making sure all the links go where
they should --- you need somebody with a really good eye for detail. If you
don't use frames, you need to create a page to reflect the state of things
FROM each link TO each link. This is doable on a small site (and I did just
this for earlier Web sites), but it's impractical for large sites; it just
gets overwhelming.

(CON) As we all know, using frames can confuse both users and browsers. It
can also force users to upgrade to browsers that support frames --- which
might cause them to abandon the site, instead! Frames can wreak havoc on the
"Back" and "Forward" buttons in the browser, and it gets even worse if the
user uses context menus (so-called right-click menus) instead: the "Back"
command will apply only to the frame where the user right-clicked, but most
users won't know this.

(PRO) Using frames can make much more of the menu tree visible at any one
time, which helps the user stay oriented --- sort of a "You are here" idea.
If you opt to include this on a single page, without frames, the navigation
tree will momentarily disappear along with the page content, whenever the
user clicks to go to a new page. This can be a bit disconcerting ---
especially on slow connections, where the page might disappear for several
seconds before anything new appears. It makes the "You are here" navigation
clues that much more important (which can reduce the space available for
navigation or content), because the latency is long enough that the user can
forget where s/he was. Not a problem when you use frames, because the menu
stays put and only the CONTENT frame changes.

(CON) Sometimes users are not aware of the connection between the "tree"
frame and the "content" frame. I've conducted several usability tests where
users weren't even AWARE that the content frame had changed, especially if
it happens quickly. They'd click the navigation-tree link several times
before they would even **check** to see what was in the content frame.
Ironically, the same latency I mentioned above, when the navigation tree and
the content are on the same page, can work to your advantage here, because
the change in display works as an attention signal.

> - Is it possible to create tree menus using DHTML and thus not require the
> entire page to reload in order to view an expanded menu?  Have you had any
> negative experiences with DHTML?

Sure, it's entirely possible, and I've done it on occasion. It's a really
tantalizing solution, but it can mean a lot of work from a pretty savvy HTML
coder. I've only had two negative experiences with this approach, but
unfortunately I just wasn't able to satisfactorily overcome them, and I
ended up going back to other solutions: (a) you need to carefully plan
around the size of everything being expanded; this means that you may have a
lot of empty white space at the bottom of the page [and inexplicable
scrollbars] when everything's collapsed --- it's setting aside that room
that it will need IN CASE the user expands everything, but it looks kind of
dorky when everything is collapsed, (b) there are still a great many browser
versions out there that don't have the necessary DHTML support to pull this
off. For instance, Netscape 4.x will just throw its metaphorical hands up in
the air and scream, "Huh??!!!??" when presented with this kind of DHTML (it
*still* doesn't do a good job of DHTML support, even in Version 7!). This
was why I went with the Java-based idea originally, although that ended up
having its own set of problems.

> - What does "VM" stand for?  Is using Java still a problem on today's
> browsers?

"VM" is the Virtual Machine, the platform-specific Java interpreter. (As a
side note, this is why Sun is so livid at Microsoft: Sun claims that
Microsoft tweaked the VM in Windows XP so as not to fully support Sun's Java
versions.) While Java was supposed to be "write once, deploy anywhere" it
didn't really work out that way at all! Even if the Java code is impeccable,
it can become an unworkable mess if the user's particular VM can't interpret
it correctly. To complicate matters even further, it isn't just a matter of
having say, a Windows VM versus a Macintosh VM --- you have the correct
**version**, too. So ultimately, Java really offered no advantage over
simply creating platform-specific versions.

The other thing to note about Java is that it's just griiiiiiiiiiindingly
slow --- partly because everything has to go through the VM and then through
the operating system and *then* through the browser. In our tests, we found
an exorbitant abandonment rate; users assumed the entire Web site had either
crashed or hung, because it was so long before anything at all happened.
Java is noticeably slow even over high-speed connections, and is just
completely impractical for dialup connections...

Which brings up the question of whether it's still a problem in modern
browsers. The short answer is, "Yeah..." because of the whole VM problem.
Even if the user is running the absolute latest browser version, s/he may be
using an older operating system and/or VM, which can still bollux the whole
shebang. Also, there's the whole issue of whether you can get away with
requiring users to upgrade their browsers --- besides the question of
whether they'll know HOW TO, even if they're willing to.

>Is Javascript a viable solution for tree menus?  Any caveats with
> Javascript?

JavaScript can do some really nifty things in this direction. The only real
caveat that I've encountered is that users do have to have it enabled in the
browser, and you can't always count on that. I'd do a "sniff" to check
whether it's enabled, and send 'em to a page with explicit instructions
(it's simple, but I don't know how savvy or un-savvy your audience is) to
turn on JavaScript. This is reeeeeeeeally minor, though, as most users have
it turned on by default, and don't even know it!

One really strong advantage to JavaScript is that it comes a lot closer than
Java (odd, but true!) to being truly cross-browser, cross-platform. Just
make sure you're not getting too fancy, as that increases the likelihood of
getting into platform-specific or browser-specific JavaScript code.

> - Can you point me to any good/bad examples of tree menus?

One interesting example is at www.acmetheater.com/acme. Look at their menu
right under the jack-in-the-box figure in the upper left. It is DHTML, so
there can be some compatibility issues, but it's a pretty good
implementation with the slide-out submenus, IMHO (although I would have
recommended doing something to make the submenus stand out from the main
page content a bit more; it can be hard to distinguish the two). Something
like this could also be done with JavaScript, which would be more work but
also more universally compatible.

One of my all-time favourites is www.davecentral.com. I think Dave actually
does this just in HTML --- plain old vanilla HTML --- which makes for fast
load times and simple maintenance, although the initial labour investment
would be pretty high. I love the simplicity of this structure (the menu tree
on the left-hand side), but if I were being picky I'd recommend indenting
the sublevels even more, to give a stronger visual cue than the
"double-line" indicator of menu level.

For the "They have the right idea, but..." category, look at
www.sleepmatters.com. Their hierarchy looks about right, their taxonomy
seems okay, but when you go to one of the menu sublevels, the visual cues
change completely, so you're not sure whether you're still within the same
taxonomy. Not sure what I mean? Try the "Products" category of the menu on
the left (it starts out as nice clean text against a sort of grey-beige
background). When you click into this subcategory, suddenly the "Products"
text is powder blue and visually separated from the product list itself. It
takes a few seconds to mentally connect this big blue "Products" text to the
little grey-beige menu choice you originally clicked, and while it's okay to
assign the powder blue to the subcategories (to distinguish them from
top-level menu choices), why is there so much distance between them and the
"Products" heading? This again slows things down until you mentally connect
the two and realize, "Oh, okay, these ARE the products and product
categories."

Hope some of you find this useful!

Jodi

*************************************
Jodi Bollaert
Usability Specialist/Information Architect
Compuware Professional Services
1-800-292-7432, ext. 10370
[log in to unmask]




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January 1997, Week 5

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