Some people are reporting that after upgrading to Snow Leopard their Address Book dashboard widget is no longer functioning properly. The widget will open and you can search for contacts properly, but when you try to present a phone number in large text by clicking on it the number will not display.
Problems with account-specific settings
In some instances the problem seems to be with accounts that have upgraded, since the problem no longer occurs after creating a new account. This therefore indicates one possibility is a corruption in settings files. If this is the case, then removing plists for Dashboard may help. Keep in mind that even though the example here is the "Address Book", these approaches can be used for any Dashboard widget.
Dashboard uses a couple of user-specific property list files, which can be refreshed by deleting them from the /username/Library/Preferences/ folder. These files are called "com.apple.dashboard.plist" and "com.apple.dashboard.client.plist" and after they are removed you should log out and back in since the dashboard runs in the background as a child process of the Dock after it is launched. You can also use the Terminal to relaunch the dock by entering the following command:
Remove and re-ad widget
Some people have found that just closing and reopening the widget itself has cleared the problem, and while deleting the preference files for the dashboard should clear your widgets and effectively do this, manually doing it is another option.
Problems with the widget itself
In other instances, this problem seems to persist even in new accounts. It could be that the widget has not been updated properly by the Snow Leopard updater. In OS X 10.5 "Leopard", the latest Address Book widget version is 1.1.5, and in Snow Leopard (at least, in version 10.6.1) the widget version is 1.2.1. Check the version of your widget by going to the Widgets folder (Macintosh HD/System/Library/Widgets/) and getting information on the widget itself. If the version you are using in Snow Leopard is not 1.2.1, there are a couple of things you can do to reinstall the widget:
From the Snow Leopard DVD
Unfortunately the latest OS X 10.6.1 update does not contain any updates to the widgets so you cannot reapply this updater to install them again; however, the Snow Leopard DVD should have all the latest versions. You can use the utility "Pacifist" from CharlesSoft to open the DVD and reinstall just the widget, which is located in the /Macintosh HD/System/Library/Widgets/ folder.
To use Pacifist, launch the program with the Snow Leopard DVD in the drive, and choose "Open Apple Install Discs" from the "File" menu. Let it scan for packages, and then expand the arrows for the following folder path:
"Contents of EssentialSystemSoftware" → "Contents of AdditionalEssentials.pkg" → Library → Widgets
With that path open, select the "Address Book.wdgt" file and choose "Install" from the top toolbar. You will need to authenticate, but the install should work smoothly and replace the current version of the widget with the selected one.
Copy from another Mac
If you have another Mac handy that has a functional Address Book widget, copy it from the /Macintosh HD/System/Library/Widgets/ folder of the functional Mac to the nonfunctional one.
The same procedure done for reinstalling the Widget with Pacifist should be used for the WebKit framework components, of which there are two that are located in the following folder trees in Pacifist (differences in bold):
"Contents of EssentialSystemSoftware" → "Contents of EssentialSystemSoftwareGroup" → "Contents of BaseSystem.pkg" → System → Library → Frameworks
"Contents of EssentialSystemSoftware" → "Contents of EssentialSystemSoftwareGroup" → "Contents of Essentials.pkg" → System → Library → Frameworks
Both components are called "WebKit.framework" and selecting and installing both with Pacifist should replace the whole framework on your system. As a fallback, if you are uncertain about using Pacifist, you can always perform an OS reinstallation, which has been refined in Snow Leopard to be more user-friendly and seamless than in prior versions of OS X.