Setting the tab policy in Swing's JTextPane

import java.awt.Dimension;

import javax.swing.JFrame;
import javax.swing.JTextPane;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultStyledDocument;

public class Tester {

    public static void main(String[] args) {
    	JTextPane textpane = new JTextPane();
    	textpane.setDocument(new TabDocument());
    	JFrame frame = new JFrame();
    	frame.getContentPane().add(textpane);
    	frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    	frame.setSize(new Dimension(200, 200));
    	frame.setVisible(true);
    }

    static class TabDocument extends DefaultStyledDocument {
    	@Override
    	public void insertString(int offs, String str, AttributeSet a) throws BadLocationException {
    		str = str.replaceAll("t", " ");
    		super.insertString(offs, str, a);
    	}
    }
}