public interface Concept {
  public String getCode();
  public String getDescription();
  public Concept setCode(String code);
  public Concept setDescription(String description);
}

public class BasicConcept implements Concept {
  private String code;
  private String description;
  @Override
  public String getCode() {
    return code;
  }
  @Override
  public String getDescription() {
    return description;
  }
  @Override
  public Concept setCode(String code) {
    this.code = code;
    return this;
  }
  @Override
  public Concept setDescription(String description) {
    this.description = description;
    return this;
  }
}

public class ConceptOne extends BasicConcept {
  private String propertyOne;
  public String getPropertyOne() {
    return propertyOne;
  }
  public ConceptOne setPropertyOne(String propertyOne) {
    this.propertyOne = propertyOne;
    return this;
  }
}

public class ConceptTwo extends BasicConcept {
  private String propertyTwo;
  public String getPropertyTwo() {
    return propertyTwo;
  }
  public ConceptTwo setPropertyTwo(String propertyTwo) {
    this.propertyTwo = propertyTwo;
    return this;
  }
}

public class Test {
  private List<Concept> concepts;
  private Concept selected;
  @Command
  @NotifyChange("selected")
  public void doReset(@BindingParam("form") Concept form) {
  }
  @Command
  @NotifyChange("concepts")
  public void doSave(@BindingParam("form") Concept form) {
  }
  public List<Concept> getConcepts() {
    return concepts;
  }
  public Concept getSelected() {
    return selected;
  }
  @Init
  public void init() {
    concepts = new ArrayList<>(2);
    concepts.add(new ConceptOne().setPropertyOne("Property 1").setCode("1").setDescription("Concept 1"));
    concepts.add(new ConceptOne().setPropertyOne("Property 2").setCode("2").setDescription("Concept 2"));
    selected = null;
  }
  public void setSelected(Concept selected) {
    this.selected = selected;
  }
}

<vlayout viewModel="@id('vm') @init('Test')">
  <listbox height="100px" model="@load(vm.concepts)"
    selectedItem="@bind(vm.selected)">
    <listhead>
      <listheader label="Code" />
      <listheader label="Description" />
    </listhead>
    <template name="model">
      <listitem>
        <listcell label="${each.code}" />
        <listcell label="${each.description}" />
      </listitem>
    </template>
  </listbox>
  <hlayout form="@id('fx') @load(vm.selected) @save(vm.selected, before='doSave')">
    <label value="Code" />
    <textbox constraint="no empty" instant="true" maxlength="64" value="@bind(fx.code)" disabled="@load(empty vm.selected)" />
    <label value="Description" />
    <textbox constraint="no empty" instant="true" maxlength="1000" value="@bind(fx.description)" disabled="@load(empty vm.selected)" />
    <button label="Reset" onClick="@command('doReset',form=fx)" disabled="@load(not fxStatus.dirty)" />
    <button label="Save" onClick="@command('doSave',form=fx)" disabled="@load(not fxStatus.dirty)" />
  </hlayout>
</vlayout>