After the article on Opera's usability on wide screens was published, I got feedback from a person in Opera's team, and found out that I haven't done my homework well.

Opera is aware of tab bloat, and they offer two solutions; right-click the toolbar, click Customize and choose one of two options for Wrapping:

• wrap to multiple lines
• show extender menu

However, these solutions are only partial ones because they do not solve the problem entirely.

This is multi-line wrapping in action (click to see a large version). You can see that it takes a lot of screen space and is not a viable solution.

I guess that not a large number of users are tab-freaks and have as many pages open as I do, but given that:

• people use hibernate often
• or they keep their machines on all the time
• the number of interesting pages on the net is very big
• a lot of RAM is not uncommon anymore (so people can "afford" many tabs)
• everything is web-based, or will soon be
• it is difficult to distinguish between two Opera windows (will be discussed in another article)
• people are lazy

It is of reason to predict that the average number of pages open at the same time will grow, even for perfectly normal people.

This is Opera's menu extender, its advantages are:

• the page titles can be read easily
• just one line is used by the tab bar
• you can see the full page titles of the non-visible tabs when you click the extender

But it has several disadvantages, one of them is a major one, though not an evident one.

Look at the current page - do you see it on the tab bar? No. If you press Ctrl+Tab to switch to another tab, the switch goes well but the tab bar itself is still not showing the current tab. In fact, what it does is always display the first N tabs (usually the ones you've opened a long time ago, which are not very relevant at the time).

The conclusion is that the tab bar should display the "neighborhood" of the current page: N pages you've opened before and N pages after (if any); N could be 5.

On Magic numbers
Five? Where did this magic number come from? Studies show that a user can mentally keep track of up to 7+/-2 entities at a time; since people are lazy, I've used the most conservative estimate. Citation needed? This is discussed in various books on programming - "how many variables can a programmed mentally keep track of at a time?"; the first one that comes to mind is McConnel's "Code Complete", but I don't remember the page number (I must've stored it in the "6th memory slot" ;-)

Without this change, the user is forced to keep in mind which were the last several pages that were used, so that they can switch between them by pressing Ctrl+Tab without having to read the title of the page on the switcher (press once = go to the previously used tab, press twice = o to the one before it, etc). Soon this information will be forgotten and the only solution is to take some time to read the titles of the pages when the tab switcher is shown, so that the titles can be "cached" again.

A more detailed explanation can be found in Donald Norman's "Design of everyday things" (use Amazon's book reader, go to page 56). The author describes how knowledge needed to use a device or a program can be stored in the user's memory or in the "the world" (i.e. program's interface). A program shouldn't heavily rely on (i.e. abuse) the user's memory, because it is limited and it is easily overwritten with new stuff.

Another problem is that the tabs in the list require great precision to be manipulated: the favicon is very small, and it is accompanied by a text description (the page title) which can only be parsed by reading it; a mental shortcut is to use the length of the title as an aid - but this only works when you have titles of different lengths.

Prediction

SVG files will become the new format for favicons, because they can be scaled to larger sizes. The benefits:

• the OS X dock-like tab bar described in the previous article will be prettier (since vector graphics is used instead of a small 16x16 raster icon)
• the tab-switcher becomes more usable because the two most important aids in hitting the right item (the icon and the title) can be bigger (remember Fitt's law)

The browser will attempt to download a favicon.svg from the site, and will use it if it is available; if not it will use the ICO and resize it via interpolation - ugly but still more usable.

This prediction trend is backed up by the "greater resolutions" trend we see today (physically small screens, but with a high resolution - imagine how a 16x16 icon looks there).

Remember, you heard it here first :-)

Conclusion

Either implement the dock-like tab-bar that

• grows bigger when the mouse approaches it
• and which displays the neighborhood of the current page by default
• and which scrolls to the right or to the left when the mouse gets closer to the edge

Or learn how to manage tab bloat in the context of the battle against information overload. Seriously, no matter how hard I try I can't have less than 20 tabs (on a clear day), is this bad?