F class and F.form, F class fields are not bound

Hi,

I've copied MyUIForm.form from the applicationConfigurable example and I've created a class. I've wired the class in my plugin.xml:

    <extensions defaultExtensionNs="com.intellij">
        <applicationConfigurable instance="org.kostaskougios.idea.preferences.SourceFolderPreferences"/>
    </extensions>


my class (a scala class) looks like:

package org.kostaskougios.idea.preferences

import javax.swing._

import com.intellij.ide.ui.UISettings
import com.intellij.openapi.options.Configurable
import com.intellij.util.ui.UIUtil

/**
* @author    kostas.kougios
*            Date: 31/07/14
*/
class SourceFolderPreferences extends Configurable
{
    private var myComponent: JComponent = _
    private var myFontName: JComboBox[String] = _
    private var myFontSize: JComboBox[String] = _
    private var MyDefaultFontButton: JButton = _
    private var myPanel:JPanel = _

    override def getDisplayName = "Scala Idea Extensions"

    override def getHelpTopic = null

    override def isModified = false

    override def createComponent() = {
        val settings = UISettings.getInstance
        myFontName.setModel(new DefaultComboBoxModel(UIUtil.getValidFontNames(false)))
        myFontSize.setModel(new DefaultComboBoxModel(UIUtil.getStandardFontSizes))
        myFontName.setSelectedItem(settings.FONT_FACE)
        myFontSize.setSelectedItem(String.valueOf(settings.FONT_SIZE))
        myComponent
    }

    override def disposeUIResources() {}

    override def apply() {}

    override def reset() {}
}

When I run my plugin, in the settings page I can see "Scala Idea Extensions" but myFontName and the rest of the fields are null. Any idea how to wire those properly?

Thanks