Look at your menubar icons, there on the top-right corner of your screen. How many do you have? If you’re a new Mac user, probably not many — I’m guessing Spotlight (by default), the clock, the battery indicator if you have a laptop, the volume icon, the AirPort icon, and perhaps the Bluetooth and Spaces icons, if you use such features.

If you’re an experienced Mac user, or just a long-time user who likes to keep up with all those useful utilities written by lots of smart Mac developers, the right side of your menubar will get increasingly crowded. Not a big deal if you work on a 20-inch display. Problematic if your main Mac is a 13-inch MacBook / MacBook Pro / MacBook Air, or worse if it’s an 11-inch MacBook Air. 

It’s easy to see why a lot of utilities want to put an icon there. The menubar is the only interface element on the Mac that is always visible (unless, of course, you’re using some application in full-screen mode), and the position of the icons there allows for a quick and easy access to any functionality they may provide. The problem, of course, is that the menubar is a finite space, and if you use a lot of third-party applications that put an icon there — either temporarily (as long as the application is open) or permanently (the application is meant to be active at login, so it’s basically an always-on process) — you will soon have to deal with it, usually by removing those you seem to be using only occasionally. 

On smaller screens this isn’t a very comfortable scenario, and even with a 15-inch screen the situation might pose a problem if you have a lot of menu extras. Firstly, you end up with a cluttered menubar, which in part prevents that quick and easy access those menu extras are made for, and secondly, when you open an application that has a long list of menu commands, they will hide some of the left-most icons, and this is a bit of a usability issue, because they may hide important status information you want to see at all times or prevent you from clicking directly on menu extras you need right away. To see them all again you usually have to switch to the Finder or to another application with fewer menu commands in the menubar.

I believe this situation is better handled on Windows, where the equivalent space in the taskbar on the bottom right of the screen is fixed by default, so only a certain number of icons can be seen all the time, and any icons in excess stay hidden unless you click on a small arrow on the left side, marked with a yellow circle in the figure below: 

I think it wouldn’t hurt to have a similar solution on the Mac, with a sort of slider that can be dragged at any time to reveal more icons or even hide them. Such an idea was actually implemented in System 7 and later in System 7.5.x with the Control Strip:

Although there were some third-party applications that still put icons in the menubar even in the System 7 era, the Control Strip allowed for more flexibility. As the Wikipedia entry says:

The Control Strip always anchors itself to the closest horizontal screen edge (left or right,) but can be freely moved up and down both sides of any display by the user. It defaults to the lower left corner of the primary display on fresh systems.

Users can choose whether to turn the Control Strip on and off and even set a hot key to hide and reveal it using its control panel. Two buttons at either end allow the Strip to be collapsed and expanded (with the one opposite the screen edge also allowing the strip to be resized when dragged), while two more buttons just inside those allow one to scroll through a very full Strip. Holding down the option key while clicking turns the cursor into a distinctive hand shape that allows one to drag the Strip around the screen, rearrange modules within the Strip and drag modules out.

The Control Strip had potential, and I remember missing it a lot when I first switched to Mac OS X. The first Dock in Mac OS X 10.0.x with its Docklings retained part of the Control Strip functionality. See my Tour of Mac OS X 10.0.3 at System Folder — there’s a screenshot showing the Docklings. In that same article I wrote:

By the way, the ‘dockling’ concept wasn’t that bad. With hindsight, using the Dock for status icons could have been a better idea, since the Dock is more expandable and eventually has more room for icons rather than the menu bar. […] [N]o matter how many icons you add to the Dock, it stretches to accommodate all of them and they’re all always visible. 

But I can see why the idea was abandoned: users with a lot of application icons and folder aliases in the Dock would have the same usability problem I was mentioning before: a Dock that is too crowded loses some of its usefulness. Also, a lot of users prefer to hide the dock when not in use, and that isn’t good if your application needs to display some status information all the time.

In the end I think that a feasible solution might be to make the right side of the menubar more versatile, giving it the ‘sliding power’ that the old Control Strip used to have — without the detachability, of course. I think that, even after six major releases, Mac OS X still lacks a bit of flexibility in some portions of its interface.