Returns the ID of the style to use if the specified style_id is not present in the current style scheme.
a style ID.
the ID of the style to use if the specified style_id is not present in the current style scheme or NULL if the style has no fallback defined. The returned string is owned by the language and must not be modified. Since 3.4
See Implementation
Returns the ID of the style to use if the specified style_id is not present in the current style scheme.