Improved Model

Added Keyboard Selection Support
Added Mouse Selection Support
Added Keyboard Editing Support
Corrected Some Bugs
Abstracted the Layout System further
Added Functions Button (test)

MathPad/MPFunction.m

@@ -24,6 +24,11 @@
 }
 
 #pragma mark Working With the Expression Tree
+- (MPExpression *)rootExpression
+{
+    return [self.parent rootExpression];
+}
+
 - (NSIndexPath *)indexPath
 {
     NSUInteger selfIndex = [self.parent indexOfElement:self];
@@ -60,7 +65,7 @@
 {
     NSUInteger index = 0;
     for (; index < [self numberOfChildren]; index++) {
-        if ([[self childAtIndex:index] isEqualToExpression:child]) {
+        if ([self childAtIndex:index] == child) {
             return index;
         }
     }
@@ -106,6 +111,7 @@
 }
 
 #pragma mark Working With Functions
+/*
 - (BOOL)isEqual:(id)object
 {
     if (self == object) {
@@ -123,7 +129,7 @@
 - (BOOL)isEqualToFunction:(MPFunction *)aFunction
 {
     return [aFunction isMemberOfClass:[MPFunction class]] && [self isMemberOfClass:[MPFunction class]];
-}
+}*/
 
 - (NSString *)description
 {