Fundamental Redesign of the View and Controller

MathPad/MPExpressionStorage.h

@@ -8,10 +8,14 @@
 
 #import "MPExpression.h"
 
-@class MPExpressionStorage, MPExpressionLayout;
+@class MPExpressionStorage, MPExpressionView, MPExpressionLayout;
 
 @interface MPExpressionStorage : MPExpression
 
+- (instancetype)initWithExpressionView:(MPExpressionView *)expressionView
+                              elements:(NSArray *)elements;
+
+@property (readonly, nonatomic, weak) MPExpressionView *expressionView;
 @property (nonatomic, strong) MPExpressionLayout *rootLayout;
 
 - (NSLayoutManager *)layoutManager;