I extended a superclass of StyledText to Add support for undo and redo operations.

First lets import a few things we are going to need:

   import java.util.LinkedList;
   import java.util.List;

   import org.eclipse.swt.custom.ExtendedModifyEvent;
   import org.eclipse.swt.custom.ExtendedModifyListener;
   import org.eclipse.swt.custom.StyledText;
   import org.eclipse.swt.widgets.Composite;

The LinkedList and List java.util routines are needed because our undo and redo additions are going to need a place to store on a couple of stacks the data to undo or redo. Lets start by creating a class "MyStyledText" that extends the SWT StyledText class.

public class MyStyledText extends StyledText {

	private class undoRedoItem {
		public Character Action;
		public int Location;
		public String Data;

		public undoRedoItem(Character Action,
		           int Location, String Data) {
			this.Action = Action;
			this.Location = Location;
			this.Data = Data;
		}
	}