title: p:commandButton vs. h:commandButton
body: <p>When I am using a PrimeFaces <code>p:commandButton</code></p>
  
  <pre><code>&lt;p:commandButton action=#{bean.action} /&gt;
  </code></pre>
  
  <p>I don't see the the validation messages for inputs (both the default <code>h:</code> ones or the PrimeFaces <code>p:</code> ones.) For example with</p>
  
  <pre><code>&lt;f:validateRequired /&gt;
  </code></pre>
  
  <p>When I am using default command button like</p>
  
  <pre><code>&lt;h:commandButton action=#{bean.action} /&gt;
  </code></pre>
  
  <p>I do see the validations. What can be the cause of this difference?</p>
  
  <p>I am using Prime Faces 3.5 with Mojarra 2.1.18</p>
  
  <pre><code>&lt;h:form id="reliefhourheadcopy-form"&gt;
  
          &lt;h:panelGrid columns="1"&gt;
              &lt;h:outputText value="Kopiere Entlastungsstunden von" /&gt;
              &lt;h:outputText value="Semester: #{reliefHourHeadManagedBean.reliefHourHead.semester}" /&gt;
              &lt;h:outputText value="Jahr: #{reliefHourHeadManagedBean.reliefHourHead.year}" /&gt;
              &lt;h:outputText value="nach" /&gt;               
          &lt;/h:panelGrid&gt;
  
          &lt;h:panelGrid columns="3"&gt;
  
              &lt;h:outputText value="Semester:" /&gt;
              &lt;p:selectOneMenu id="semester" value="#{reliefHourHeadManagedBean.semester}"&gt;
                  &lt;f:selectItems value="#{reliefHourHeadManagedBean.semesterTypes}" /&gt;
              &lt;/p:selectOneMenu&gt;
              &lt;h:message for="semester" /&gt;
  
              &lt;h:outputText for="yearSpinner" value="Jahr:" /&gt;
              &lt;p:spinner id="yearSpinner" value="#{reliefHourHeadManagedBean.year}" maxlength="4" min="2000" max="2030" size="4"&gt;
                  &lt;f:validateRequired /&gt;
                  &lt;f:validateLongRange minimum="2000" maximum="2030" /&gt;
              &lt;/p:spinner&gt;
              &lt;h:message for="yearSpinner" /&gt;
  
          &lt;/h:panelGrid&gt;
  
          &lt;h:panelGrid columns="1" style="margin-top:25px"&gt;
              &lt;p:commandButton action="#{reliefHourHeadManagedBean.copyReliefHourHead}" value="Kopieren" icon="ui-icon-copy" &gt;
                  &lt;f:param name="reliefhourhead_id" value="#{reliefHourHeadManagedBean.reliefHourHeadId}" /&gt;
              &lt;/p:commandButton&gt;
          &lt;/h:panelGrid&gt;
  
      &lt;/h:form&gt;
  </code></pre>