See the http://mail.openjdk.java.net/pipermail/macosx-port-dev/2014-March/006516.html

Unfortunately, at least one icon was (partially) missed - the expand tree control (that little triangle).

It is rendered in HiDPI, when you click on it, but in its regular appearance it is low res.

The problem occurs on OS X 10.9.2 with

java version "1.8.0_20-ea"
Java(TM) SE Runtime Environment (build 1.8.0_20-ea-b05)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b05, mixed mode)


Cheers,

-hendrik


Source code to illustrate the issue - a plain vanilla JTree. Just play with the expansion triangles.
------------------
import javax.swing.*;
import java.awt.*;

public class TreeExpanders {

    public static void main(String[] args) {
        final JFrame frame = new JFrame();
        final JTree tree = new JTree();
        frame.getContentPane().setLayout(new BorderLayout());
        frame.getContentPane().add(tree, BorderLayout.CENTER);
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                frame.setBounds(200, 200, 200, 200);
                frame.setVisible(true);
            }
        });
    }
}
------------------