imrpoved UI system structure and added a basic text module for testing; Untested.

RhythmBullet/Zer01HD/UI/Book/Book.cs

@@ -0,0 +1,45 @@
+using Microsoft.Xna.Framework.Graphics;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RhythmBullet.Zer01HD.UI.Book
+{
+    class Book
+    {
+        Viewport viewport;
+        Dictionary<string, Page> pages = new Dictionary<string, Page>();
+        public Book(Viewport viewport)
+        {
+            this.viewport = viewport;
+        }
+
+        public void AddPage(Page page)
+        {
+            pages.Add(page.Name, page);
+        }
+
+        public void RemovePage(Page page)
+        {
+            RemovePage(page.Name);
+        }
+
+        public void RemovePage(string name)
+        {
+            pages.Remove(name);
+        }
+
+        public void Resize(int width, int height)
+        {
+            viewport.Width = width;
+            viewport.Height = height;
+        }
+
+        public void DisplayPage(string name)
+        {
+            pages[name].DisplayWithViewport(viewport);
+        }
+    }
+}

RhythmBullet/Zer01HD/UI/Book/Page.cs

@@ -0,0 +1,36 @@
+using Microsoft.Xna.Framework.Graphics;
+using RhythmBullet.Zer01HD.UI.Modular;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RhythmBullet.Zer01HD.UI.Book
+{
+    class Page : ModuleGroup
+    {
+        private readonly int pageX, pageY;
+
+        public Page(int pageX, int pageY, int width, int height)
+        {
+            this.pageX = pageX;
+            this.pageY = pageY;
+            ApplySize(width, height);
+        }
+
+        public virtual void ApplySize(int width, int height)
+        {
+            X = pageX * width;
+            Y = pageY * height;
+            this.Width = width;
+            this.Height = height;
+        }
+
+        public void DisplayWithViewport(Viewport viewport)
+        {
+            viewport.X = X;
+            viewport.Y = Y;
+        }
+    }
+}