Use ExtendedModifyEvent : StyledText Event « SWT « Java Tutorial

Call addExtendedModifyListener() to add an ExtendedModifyListener.

ExtendedModifyEvent Fields

Field	Description
int start	The zero-based offset, relative to the start of the StyledText, of the first position of the changed text.
int length	The length of the changed text, in characters.
String replacedText	The text that was replaced by this change.

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.ExtendedModifyEvent;
import org.eclipse.swt.custom.ExtendedModifyListener;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class StyledTextExtendedModifyListener {
  public static void main(String[] args) {
    final Display display = new Display();
    final Shell shell = new Shell(display);

    final StyledText styledText = new StyledText(shell, SWT.V_SCROLL | SWT.BORDER);
    styledText.setText("12345");

    styledText.addExtendedModifyListener(new ExtendedModifyListener() {
      public void modifyText(ExtendedModifyEvent event) {
        System.out.println(event.start);
        System.out.println(event.length); 
        System.out.println(event.replacedText);
      }
    });

    styledText.setBounds(10, 10, 100, 100);
    shell.open();
    while (!shell.isDisposed()) {
      if (!display.readAndDispatch()) {
        display.sleep();
      }
    }
    display.dispose();
  }
}

17.45.StyledText Event
	17.45.1.	Handling Events
	17.45.2.	Filtering Change with VerifyKeyListeners
	17.45.3.	Allow backspace and delete
	17.45.4.	Allow Arrow Key
	17.45.5.	Allow return
	17.45.6.	After all VerifyKeyListeners are notified, any VerifyListeners are then notified.
	17.45.7.	Print out VerifyEvent detail
	17.45.8.	Against cut-and-paste: Modify the data in VerifyEvent to change the effect of user's keystrokes
	17.45.9.	Veto the event by setting its doit member to false.
	17.45.10.	Reacting to Change
	17.45.11.	Add Paint event listener to StyledText
	17.45.12.	Use a verify listener in StyledText
	17.45.13.	Add Paint Object Listener
	17.45.14.	Dragging text in a StyledText widget
	17.45.15.	Use ExtendedModifyEvent