Normaly, the invalidation occurs only when we are setting the top level properties of this class
When set, the setter invalidates the style state
When changing Unity properties (e.g. label.Style.NormalColor.textColor = Color.yellow;) we have no way of registering the inner settings
However, we present this parameter which, when set to true, invalidates a style on each request (e.g. get)
Use carefully!

C# | Visual Basic | Visual C++ |
public GUIStyle Style { get; set; }
Public Property Style As GUIStyle Get Set
public: virtual property GUIStyle^ Style { GUIStyle^ get () sealed; void set (GUIStyle^ value) sealed; }