Mac OS X has made multitasking an everyday occurrence for Mac users—you can let long-running tasks complete in the background while you use your computer for other things. But this capability has introduced a new problem: knowing the status of background tasks.
Software developers have struggled with this problem. Some have opted to take advantage of the Dock, altering their application’s Dock icon to indicate when certain events have occurred (or completed). Unfortunately, a Dock icon affords a very limited amount of space and can convey only so much information. Some developers use dialog boxes, but these either interfere with the user—by taking over the screen—or appear in the background, with the user remaining unaware of their presence. (Dialogs also require the user to acknowledge them.)
Until recently, a good notification mechanism wasn’t readily available. The open-source (and free) Growl aims to be that mechanism. Quite simply, Growl’s objective is to act as a conduit, receiving event information from applications and displaying that information however the user chooses.
Growl provides ten different notification styles including such styles as Bubbles and MailMe. Each style has its own set of options, controlling things such as which screen to display on, opacity, display duration, and color options. But the display doesn’t have to be just visual; for example, email and speech notification can also be used.
The Bubbles style
The MailMe style preferences
Third-party developers can also construct their own; one such style is Spongebob Squarepants:
Spongebob Squarepants style
Growl support isn’t inherent to Mac OS X applications—it requires that explicit support be added by the developer. Applications that feature Growl support include Adium, FlickrExport, GmailStatus, NewsFire, Skype, and Synergy. Other applications have gained support through third party plugins and monitoring applications. Applications of this class include Safari, iChat, Mail.app, Entourage, NetNewsWire (using NewsGrowl ), and Sailing Clicker. Growl’s Web site provides a complete list of supported applications.
NewsGrowl displayed with the Smoke Style
The multitude of alerts can be overwhelming, so a good deal of customization is available to keep it under control. For example, each application has its own set of events. Each event can be turned on or off; use a different style or priority; and even made “sticky” (wherein a notification does not go away until explicitly acknowledged). Styles can be picked at an application level so that all notifications from a particular application use a specific style. For example, one may want to use the Music Video style for Synergy events (from iTunes). With even finer event level control, Music Video can be used to indicate the start of a new song, with Bubbles Style used when songs are paused.
Growl also includes a Network feature, allowing for notifications to be sent from one computer to another. For example, while using your laptop, you could receive updates from your desktop Mac elsewhere in your house or office. Unfortunately, the current implementation of this feature has a few flaws. For one, Growl can hang if the computer to which you are forwarding is not turned on and awake. Further, feedback loops are possible when two computers forward their notifications to one another—a notification will repeat itself endlessly on both computers, resulting in odd effects with some styles.
That said, Growl is fully functional and very promising for software that’s at only version 0.7. As new notification styles are added and more applications add support, this software will become indispensable for any multitasker.