Extensions.HW.prototype.isAvailable = function HW$isAvailable(selection, pipeline)
{
 var items = selection.getItems();
  var item = $models.getItem(selection.getItem(0));

if (items.length >= 1 &&  item.getItemType() == $const.ItemType.COMPONENT ) {
    return true;
    }
    else {
        return false;
    }
};

Extensions.HW.prototype.isEnabled = function HW$isEnabled(selection, pipeline) {
    var items = selection.getItems();
     var item = $models.getItem(selection.getItem(0));
    if (items.length >= 1 && item.getItemType() == $const.ItemType.COMPONENT ) {
            return true;
    }
    else {
        return false;
    }
};

<cfg:dependency>HelloWorldRibbon.Commands</cfg:dependency>
      </ext:dependencies>

      <ext:apply>
        <ext:view name="DashboardView">
          <ext:control id="DashboardToolbar" />
            </ext:view>
         <ext:view name="ComponentView">
          <ext:control id="ItemToolbar" />

        </ext:view>

      </ext:apply>
    </ext:extension>