Selection.StyleKeepFmt Property (Visio)
Applies a style to an object while preserving local formatting. Read/write.
Setting a style to a nonexistent style generates an error.
Beginning with Microsoft Visio 2002, setting StyleKeepFmt to an empty string ("") will cause the master's style to be reapplied to the shape. (Earlier versions generate a "no such style" exception.) If the shape has no master, its style remains unchanged.