Yesterday I discovered something weird about the GNOME panel's workspace switcher, which I could not find in the official documentation. It is based on the meaning given to those workspaces that the above mentioned applet is supposed to switch.

As you may know, the concept of virtual workspace may refer to two different mechanisms, which can even be present at the same time.

1. You can have multiple distinct desktops, all independent from each other. You can view only one desktop at a time. The windows can reside on each one of them, and you can send windows from one desktop to the other.
2. The size of every single desktop can be higher than the screen size. In that case you only see a portion of the desktop at a time, and that is called a viewport. If your desktop is 4 times the width of the screen, you have 4 possible viewports. The windows can appear on every viewport, and even across the border between adjacent viewports.

If you use Compiz, for example, you can have both multiple desktops (setting the gconf option number_of_desktops) and multiple viewports (setting the options hsize and vsize), but only viewports can be hosted on the faces of the famous spinning cube.

The GNOME panel has an applet that shows the content of the different workspaces and let you switch from one to another. GNOME documentation uses the term workspace without specifying if it refers to desktops or viewports.

Now, I have discovered this weird rule: if there are more than one desktop, GNOME's term workspace means desktop, but if there is only one desktop, then it immediately means viewport.

I find this undocumented "feature" very counter-intuitive, and indeed it can lead the unaware user to hours of frustration.