FULL PRODUCT VERSION :
java version "1.5.0_05"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_05-b05)
Java HotSpot(TM) Client VM (build 1.5.0_05-b05, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [Version 5.1.2600]

A DESCRIPTION OF THE PROBLEM :
Users cannot see what lines were selected if the lines consist of line separators('\n')  only.
The behaviour was changed by fixing another bug (http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4855860). Width for a child view '\n' is set to 0 therefore the selection is not visible.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Compile and run. You don't see anything selected on 1.5.0_05. Users could be
confused from this behaviour. Line separators should have non zero width
while selecting text(for empty lines).


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Selection painter should handle this.
ACTUAL -
Selection for empty these lines is not visible.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------

import javax.swing.*;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;

/**
 * Bug Preview for empty selection - selection of empty lines
 */
public class BugPreview {
    final static String endOfLineProperty =
System.getProperty("line.separator", "\n");

    private static void addEmptyLine(JTextComponent c) throws
BadLocationException {
        final Document document = c.getDocument();
        document.insertString(document.getLength(), endOfLineProperty,
null);
    }

    public static void main(String[] args) {
        JTextComponent editor = new JTextPane();
        try {
            addEmptyLine(editor);//a few empty lines
            addEmptyLine(editor);
            addEmptyLine(editor);
        } catch (BadLocationException e) {
            e.printStackTrace();
        }
        editor.selectAll(); // now we select all text, but empty lines are not marked as selected on 1.5.0_05
        JFrame frame = new JFrame();
        frame.setTitle("Demo");
        frame.setSize(200, 150);
        frame.getContentPane().add(editor);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

---------- END SOURCE ----------

Release Regression From : 1.4.2_09
The above release value was the last known release where this 
bug was known to work. Since then there has been a regression.