Fixed mask for image fields, added mask support to slice window

git-svn-id: svn://svn.code.sf.net/p/magicseteditor/code/trunk@243 0fc631ac-6414-0410-93d0-97cfa31319b6

src/data/field/image.hpp

@@ -39,6 +39,8 @@ class ImageStyle : public Style {
 	
 	Scriptable<String> mask_filename; ///< Filename for a mask image
 	
+	virtual bool update(Context&);
+	
   private:
 	DECLARE_REFLECTION();
 };