Hello,
By default JForex platform on Linux use Nimbus Java Look And Feel.


Can I change it to GTK+ Java Look And Feel?


With default Nimbus Java Look And Feel there are some bugs, for example viewtopic.php?f=85&t=50406&p=76319 or viewtopic.php?p=75841#p75841

I try to uncomment line

swing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel

in file /usr/lib/jvm/java-7-openjdk-i386/jre/lib/swing.properties but no result.

Kubuntu 13.10

Don't use OpenJDK. There are issues with that java implementation.
Use java from oracle.

I don't think so it will solve your issue about Look&Feel, but it worth to replace the openJdk.

Try this code:

package jforex;

import com.dukascopy.api.IAccount;
import com.dukascopy.api.IBar;
import com.dukascopy.api.IContext;
import com.dukascopy.api.IMessage;
import com.dukascopy.api.IStrategy;
import com.dukascopy.api.ITick;
import com.dukascopy.api.Instrument;
import com.dukascopy.api.JFException;
import com.dukascopy.api.Period;
import com.dukascopy.api.RequiresFullAccess;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

@RequiresFullAccess
public class SetGtkLookAndFeel implements IStrategy {

    public void onStart(IContext context) throws JFException {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception ex) {
            context.getConsole().getOut().println(ex);
        }
        SwingUtilities.updateComponentTreeUI(context.getUserInterface().getMainFrame());
        context.stop();
    }

    public void onTick(Instrument instrument, ITick tick) throws JFException {}
    public void onBar(Instrument instrument, Period period, IBar askBar, IBar bidBar) throws JFException {}
    public void onMessage(IMessage message) throws JFException {}
    public void onAccount(IAccount account) throws JFException {}
    public void onStop() throws JFException {}
}

It is not perfect but this is a way.

Thanks but it is not good idea. I try this code but there are many bugs in grafical interface of JForex platform.