Tab Index
Scope
- Book Page content object > Bubble object > Tab Index property
- Book Page content object > Image object > Tab Index property
- Book Page content object > Page object > Tab Index property
- Book Page content object > Placeholder object > Tab Index property
- Book Page content object > Shape object > Tab Index property
- Book Page content object > Text object > Tab Index property
Purpose
The Tab Index property can be used to identify the order in which objects on the Book Page should be 'given the focus' (that is, become the 'active object') when the user successively presses the Tab key during playback. The first press on Tab will transfer focus to the object with a Tab Index property value of 1, and so on until all objects with a Tab Index property value have been visited, after which the remaining objects on the Book Page (with a Tab Index property value of 0) are tabbed through in seemingly random order (there may be some logic to this, but I can't figure out what it is - it's not left-to-right, nor in 'layer' order...).
If the user presses the Enter key on the keyboard when an 'action' object has the focus, then this effectively performs the On Click action for the object. Specifying Tab Index properties for these objects is therefore a good way of adding a way for users to interact with your content without using the mouse. Some accessibility proponents suggest this is a good thing to do.
Note that some Book Page objects have sub-objects (such as the Close button in a Bubble object), so successive Tabs may not necessarily cycle through every object in strict Tab Index order (that is, pressing Tab four times is not guaranteed to land on the object with a Tab Index of 4.
