mport javafx.collections.ObservableList;
import javafx.scene.control.ComboBoxBuilder;
import javafx.scene.control.SliderBuilder;
import javafx.scene.control.TextFieldBuilder;
import javafx.scene.layout.HBoxBuilder;
import javafx.scene.layout.VBoxBuilder;


public ConversionPanel(String title, ObservableList<Unit> units, 
DoubleProperty meters) {
    setText(title);
    setCollapsible(false);
    setContent(HBoxBuilder.create()
            .children(
                VBoxBuilder.create()
                    .children(
                        textField = TextFieldBuilder.create()
                            .build(),
                        slider = SliderBuilder.create()
                            .max(MAX)
                            .build()
                    )
                    .build(),
                comboBox = ComboBoxBuilder.<Unit>create()
                    .items(units)
                    .converter(new StringConverter<Unit>() {
                
                @Override
                public String toString(Unit t) {
                    return t.description;
                }

                 @Override
                 public Unit fromString(String string) {
                    throw new UnsupportedOperationException("Not supported yet.");
                 }
            })
            .build()
      )
      .build());
this.meters = meters;

comboBox.getSelectionModel().select(0);
}