Browsing Actions
The Zoom Tool is used to activate actions that are associated with certain graphics.
Graphics in OmniGraffle documents can have actions attached to them (URL links or AppleScript scripts) via the Action Info pane; these actions can be activated by clicking graphics with the Browse tool. Once you switch to the Browse tool, the mouse cursor will become a pointing hand; when you move the cursor over a graphic with an attached action, the graphic will highlight. Click to activate the action.

Clicking a graphic with a URL action will open the URL using your preferred application for opening URLs of that type; for example, "mailto:" URLs will open in your email application, and "http:" URLs will open in your web browser. (To choose which applications open which types of URLs, use the Internet pane of System Preferences. See Mac Help for more information.) Clicking a graphic with a "file:" URL is equivalent to double-clicking the referenced file in the Finder.

Clicking a graphic with an attached AppleScript will run the script. If a script error is encountered, a sheet will appear explaining it.