Use a verify listener in StyledText : StyledText Event « SWT « Java Tutorial

1. Java Tutorial
2. SWT
3. StyledText Event

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.events.VerifyEvent;
import org.eclipse.swt.events.VerifyListener;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class StyledTextListenerVerify {
  public static void main(String[] args) {
    final Display display = new Display();
    final Shell shell = new Shell(display);
    shell.setLayout(new GridLayout());
    StyledText styledText = new StyledText(shell, SWT.WRAP | SWT.BORDER);
    styledText.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
    styledText.setText("text");

    // use a verify listener to keep the offsets up to date
    styledText.addVerifyListener(new VerifyListener() {
      public void verifyText(VerifyEvent e) {
        System.out.println(e.start);
        System.out.println(e.start);
        System.out.println(e.text.length());
      }
    });

    shell.setSize(400, 400);
    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