Member variable XbpToolBarButton():key Foundation

The :key instance variable contains a character string that can be used to uniquely identify a button object within its XbpToolBar container. While the ordinal position of a tool bar may change as buttons are added or deleted at run time, a button's key string must be unique over the lifetime of the toolbar object. If an attempt is made to add a button with a duplicate key string, or if the key of an existing button is to be set to a duplicate value, a runtime value is generated.

The key string assigned to a given tool bar button can be specified using the <cKey> parameter to XbpToolBar:addItem(). Alternatively, a button's :key instance variable may be used to change its key string after it has already been added to an XbpToolBar instance.

// An example for using :key to distinguish between 
// individual buttons defined in an XbpToolBar 
// instance can be found under method :loadImageSet()