Some applications provide a dockling you can use to work that application (as more applications are created for Mac OS X, you can expect that more applications will take advantage of this feature). Some applications are provided as a dockling that you install on the Dock to take advantage of its features (see Figure 5.6).
Using docklings is similar to other items on the Dock. Click the dockling to open its list of commands or options. If the dockling is for an application, you can open the application (if it is closed) or use its controls (if the application is open). For example, when iTunes is open, you can Control+click its icon to pop up a menu from which you can control music playback. If the dockling provides control over your system, open the menu and choose the settings you want.
The docklings installed on a Dock are specific to each user account. However, the same docklings can be installed on the Dock for each user or each user can install only those docklings that they want to be able to use.
To install a dockling, drag it to the Dock. (As mentioned earlier, docklings can be placed anywhere on the Dock.)
When you install a dockling, the dockling will be installed only on the Dock of the Administrator who installed that dockling on the machine. However, any user can drag the dockling to the Dock for that user account.
For this reason, you should always store docklings you want other users to be able to add to their Docks in a Public directory so that every user will be able to access them (to install them on their Docks).