if a style is used, it can not be modified agaign. so i need a clone method. but its hard to implement.
what i want to do is implementing a cascading 'style' mechanism. for example, i set two style to the same frameworkelement. the same property of latter style will override the former one, while the different property remain unchanged. but if i set the style property of the frameworkelement twice directly, the 1st style will be gone. so i use the baseon property of style class to do that. but now come across another problem, the style can not be modified after it's been set to a frameworkelement. so now i need a clone method.