Implementation of Lexi editor as described in Gang of Four's Design Pattern Book.

All the following Design Patterns are implemented in this Editor;

1. Composite: Creating a Glyph hierarchy (Character, Glyph and recursive composition), Row
2. Strategy: Line breaking algorithm
3. Decorator: To add a Scrollbar dynamically at runtime and also removing it
4. Command: Implementation of Command pattern (encapsulating requests as objects) and all undo, redo, command history management Implemented Commands are: Font Size Increase, Decrease, Bold, Italic, Insert, Delete
5. Observer: Classic implementation of Observer pattern. Try to load the Editor with a same mode and multiple views. Right now it runs this way.
6. Visitor: Full visitor pattern implementation for spell checking. It can highlight the misspelled words in red,
7. Multiline selection by mouse drag, Glyph Highlight is done.
8. Singletone In CommandManager Class