title: p:selectOneMenu list display
body: <p>I have some problem with p:selectOneMenu. My selectOneMenu will populate a list with grouping. If the list is too long, the list get displayed upwards without any vertical scrollbar. It should display downwards with a vertical scrollbar. </p>
  
  <p>If the selectOneMenu is populated with normal list without grouping, it works fine. List can display with a vertical scrollbar if its too long.</p>
  
  <pre class="lang-xml prettyprint-override"><code>&lt;p:selectOneMenu id="abcd_combo_box_ctpy2" styleClass="selectOneMenu"&gt;
      &lt;f:selectItems value="#{pc_Abcd.carList2}" &gt;&lt;/f:selectItems&gt;
  &lt;/p:selectOneMenu&gt;
  </code></pre>
  
  <pre class="lang-java prettyprint-override"><code>public List getCarList2() {
  
      List cars;
  
      SelectItemGroup g1 = new SelectItemGroup("German Cars");
      g1.setSelectItems(new SelectItem[] { 
              new SelectItem("BMW", "BMW"),
              new SelectItem("Mercedes", "Mercedes"),
              new SelectItem("Volkswagen", "Volkswagen"), 
              new SelectItem("Item 1", "Item 1"), 
              new SelectItem("Item 2", "Item 2"), 
              new SelectItem("Item 3", "Item 3"), 
              new SelectItem("Item 4", "Item 4"), 
              new SelectItem("Item 5", "Item 5"), 
              new SelectItem("Item 6", "Item 6"), 
              new SelectItem("Item 7", "Item 7"), 
              new SelectItem("Item 8", "Item 8"), 
              new SelectItem("Item 9", "Item 9"), 
              new SelectItem("Item 10", "Item 10"), 
  
      });
  
      SelectItemGroup g2 = new SelectItemGroup("American Cars");
      g2.setSelectItems(new SelectItem[] {
              new SelectItem("Chrysler", "Chrysler"),
              new SelectItem("GM", "GM"), 
              new SelectItem("Ford", "Ford"),
              new SelectItem("Item 21", "Item 21"), 
              new SelectItem("Item 22", "Item 22"), 
              new SelectItem("Item 23", "Item 23"), 
              new SelectItem("Item 24", "Item 24"), 
              new SelectItem("Item 25", "Item 25"), 
              new SelectItem("Item 26", "Item 26"), 
              new SelectItem("Item 27", "Item 27"), 
              new SelectItem("Item 28", "Item 28"), 
      });
  
      cars = new ArrayList();
      cars.add(g1);
      cars.add(g2);
  
      return cars;
  } 
  </code></pre>