Alignment issue on p:selectOneMenu

When <p:selectOneMenu /> aligns with other components.
It is align slightly upper than other components.

To resolve this issue.
simply put each component into each individual <td /> or a panelGrid to wrap the components.

<h:panelGrid columns="3">
  <p:inputText></p:inputText>
  <p:commandButton value="test"></p:commandButton>
  <p:selectOneMenu>
    <f:selectItem itemLabel="select" itemValue=""/>
  </p:selectOneMenu>
</h:panelGrid>

output:

Done!!