While we realize that a majority of our readers (and the world at large) use Windows, it's obvious that Canonical is getting its inspiration from Apple's Mac OS X and not Microsoft's ubiquitous OS. Therefore, we cannot help but compare Unity, and the Launcher especially, to the Mac OS X dock.
The one thing Unity's Launcher has in common with the Windows 7 Superbar is that the background of Launcher entries take on the prominent color of the application's icon.
In Unity, the left side of the screen contains the Launcher. Like the global menu, the Launcher takes heavy cues from OS X. For the most part, the Launcher is the OS X dock, only on the left side of the screen instead of the bottom. The Launcher is made up of five main elements (from top to bottom): pinned launchers (quick launch), running applications (task bar), Workspace Switcher (virtual desktops), Lenses, and Trash. Let's go over each element one-by-one.
The first pinned entry in the Unity Launcher is the Home folder. This opens your /home/username directory in Nautilus (the GNOME file manager). Similarly, the first entry in the OS X dock is the Finder (the OS X file manager), which also opens your home directory.
Directly below the Home folder is where quick launchers for other applications go. By default, Ubuntu 11.04 has launchers for Firefox, LibreOffice Writer, Calc, Impress, the Ubuntu Software Center, and Ubuntu One. These application launchers serve as both quick launch shortcuts to start applications and taskbar entries if the app is currently running.
In order to differentiate launchers from running tasks, a small white triangle appears on the Launcher to the left of any application that is currently running. This is similar to the small white dot that appears below open applications in the OS X dock.
If an application is currently selected (in the foreground), its Launcher icon receives a small white triangle to the right.
In Unity, multiple white triangles appear if an application is using more than one window. If an application does have more than one window open, clicking on the Launcher entry will activate window spread. Spread is a Compiz effect that locks the Launcher and zooms out to show all of the application's windows on-screen together. Simply click on a window to bring it to the foreground.
The video below shows window spread in action.
Open applications not pinned to the Launcher get an icon below the pinned applications. In the screenshot below, Firefox (pinned) is the foreground app, and therefore has the right-side triangle. The left-side triangles indicate that LibreOffice Calc, Banshee, and the Disk Utility are also open. Since Calc is using three windows, its Launcher entry gets three left-side triangles, and because Banshee and Disk Utility are not pinned to the launcher, their icons are placed between pinned applications and the Workspace Switcher.
Ubuntu previously handled virtual desktops (additional desktops or workspaces, whatever you want to call them) via the desktop switcher applet in the far-right end of the lower panel. By default, the desktop switcher applet was represented by a rectangular strip separated into four squares. Each square represented one of four virtual desktops, and clicking on one of the four squares switched to the corresponding desktop.
In Unity, the Workspace Switcher is the first grey Launcher item, appearing immediately after unpinned applications. Selecting the Workspace Switcher from the Launcher causes the Launcher to lock and the desktop to zoom out, revealing four desktops. The slick animations are provided by the Desktop Wall and Expose plug-ins for Compiz.
The video below demonstrates the new Workspace Switcher in action.
Lenses are a new way to quickly access anything on the computer, from applications to files to people. By default, the Unity Launcher comes with the Applications and Files & Folders Lenses. They are located right below the Launcher entry for the Workspace Switcher. Clicking a Lens brings up a Dash screen specifically tailored to the selected Lens.
Lenses also provide right-click menus for quickly narrowing down specific results within the Lens, before Dash is activated. For example, right-clicking the Applications Lens brings up a categorized menu of applications similar to traditional Start menus. Categories contained in the Applications Lens include: All Applications, Accessories, Universal Access, Developer Tools, Education, Science & Engineering, Games, Graphics, Internet, Multimedia, Office, Themes & Tweaks, System, and the somewhat-redundant Applications.
Clicking the the Files & Folders Lens brings up the same Dash screen as the Find Files shortcut from the Dash home screen with sections for Recent, Downloads, and Favorite Folders. Right-clicking the Files & Folders Lens brings up a menu to narrow down different types of files and folders. By default these options include: All Files, Documents, Folders, Images, Audio, Video, Presentation, Other, and Files & Folders. As with the Applications Lens, the All Files and Files & Folders options both take you to the same Dash screen: the Find Files shortcut from the Dash home screen.
It should be noted that Lenses have their own API, and therefore anyone with the know-how can make a custom Lens and share it with the world. We expect there will be many custom Lenses available in the next release, Ubuntu 11.10 Oneric Ocelot.
The trash is still the trash, just with a prettier icon. Left-clicking the Trash opens it in the Nautilus file manager, while a right-click brings up the option to Empty Trash.
When an application is maximized in Unity, the Launcher slides out of the way to emphasize full-screen applications. In order to bring the Launcher back, one must move the cursor to the top-left corner of the screen, or rest the cursor anywhere on the left side of the screen for a few seconds. The video below demonstrates the auto-hide behavior of the Unity Launcher.
Unfortunately, as of right now, there is now way to disable the auto-hide feature without installing additional packages and doing some tweaking.
If there are too many Launcher entries for all of them to appear on-screen at the same time, the lower Launcher entries collapse like tiles or cards. Using the mouse scroll wheel over the Launcher, or simply dragging Launcher entries up or down, scrolls through the Launcher. The video below demonstrates this:
Organizing the Launcher
There are two methods for adding applications to the Unity Launcher. The first involves opening the desired application and right-clicking its unpinned Launcher entry. The right-click menu has the option to Keep in Launcher. When selected, the Launcher entry moves to the bottom of the pinned application section, above unpinned applications. Right-click on a pinned Launcher entry and select Keep in Launcher again to remove it.
The second method to add items to the Launcher is through Dash. You can drag applications from Dash to the Launcher. This method allows you to decide exactly where the Launcher entry will go in the sequence of pinned entries. You can also reorganize where Launcher entries appear in the Launcher. To do this, drag the desired Launcher entry to the right, off of the Launcher, and then back onto the Launcher in the desired area. The video below shows how to add Launcher entries from Dash, as well as how to re-organize existing Launcher entries.