You are probably asking yourself why I included Smart Tags in a book on visualizing information. Well, Smart Tags can be live indicators of the value of Shape Data because they can highlight information that needs your scrutiny.
Many years ago, I used to use a UNIX computer-aided design (CAD) system that could be linked to a database. Whenever I demonstrated color number 255, the clients always looked on with renewed interest. Color 255 was simply flashing red, and always successfully drew attention to the flashing item. Visio does not have any built-in flashing colors, but it does have Smart Tags. These can grab your attention because they can always be on (and at a constant size, regardless of the zoom level), they can appear whenever you move the mouse over a shape, or they can appear whenever a shape is selected. In fact, they are better than flashing red because they can also have rollover text and a pull-down menu, and that is the link with Actions on the right mouse menu!
In fact, Smart Tags provide a visible anchor for Actions that are revealed as menu items by the down arrow on the right of the Smart Tag. These Actions can indirectly run code in Visual Basic for Applications (VBA), in an Add-In or an Add-on, or they can change the values in other ShapeSheet cells.
Just one thing, though, Smart Tags do not print and they do not show in any interface (including the Visio Viewer control) except for Visio and the Visio Drawing control! Therefore, they are only useful for capturing the Visio user’s attention. In fact, a user can switch off their display altogether using the View tab on the Tools \ Options dialog.