It may help but you could put a controller bean into the mix.

Oh, sorry if that wasn't clear, I am using a controller class that inherits from Seam's EntityHome. It doesn't seem to be a problem there, however, because I got the same results when I created a simple session bean and used it as the target for the button's action.

I tried tracing the problem within RichFaces, it looks like no button pressed event is broadcast in the Invoke Application phase (but only when a postback happens due to validation errors prior to this submission).

Here's the code of a page where it happens:

<!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
                             "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<ui:composition xmlns="http://www.w3.org/1999/xhtml"
                xmlns:s="http://jboss.com/products/seam/taglib"
                xmlns:ui="http://java.sun.com/jsf/facelets"
                xmlns:f="http://java.sun.com/jsf/core"
                xmlns:h="http://java.sun.com/jsf/html"
                xmlns:a="http://richfaces.org/a4j"
                xmlns:rich="http://richfaces.org/rich"                 
                template="layout/powderpuff.xhtml">
                       
<ui:define name="body">

  <h:messages globalOnly="false" styleClass="message" id="globalMessages"/>
    
    <h:form id="post" styleClass="edit">
      <rich:panel rendered="#{postHome.instance.parent ne null}">
        <f:facet name="header">#{messages.inReplyTo}</f:facet>
        <ui:include src="/discussion/singlePost.xhtml" >
           <ui:param name="post" value="#{postHome.instance.parent}" />
           <ui:param name="repliable" value="false" />
        </ui:include>
      </rich:panel>
    
      <rich:panel>   
        <div class="dialog">
            <s:validateAll>                
                
                    <s:decorate id="titleDecoration" template="/layout/edit.xhtml">
                        <ui:define name="label">#{messages.title}</ui:define>
                        
                        <h:inputText id="title"
                               required="true"
                               size="100"
                                  value="#{postHome.instance.title}">
                            <!-- a:support eventsQueue="validationQueue" event="onblur" reRender="titleDecoration"/-->
                        </h:inputText>
                    </s:decorate>                                        

                    <s:decorate id="bodyDecoration" template="/layout/edit.xhtml">
                        <ui:define name="label">#{messages.body}</ui:define>
                        <h:inputTextarea id="body" cols="60" rows="10"
                                  value="#{postHome.instance.body}">
                            <!-- a:support eventsQueue="validationQueue" event="onblur" reRender="bodyDecoration"/-->
                        </h:inputTextarea>                      
                    </s:decorate>
            </s:validateAll><script type="text/javascript">                        
              WYSIWYG.attach('post:bodyDecoration:body',full);                         
            </script>
        </div>
        <div style="clear: both;">&nbsp;</div>
        <div><span class="required">*</span> <h:outputText escape="false" value="#{messages.requiredFields}"/></div>
        </rich:panel>
        
        <div class="actionButtons">

            <h:commandButton id="save" 
                          value="#{messages.save}" 
                         action="#{discussionController.persistPost}"
                       disabled="#{!postHome.wired}"
                       rendered="#{!postHome.managed}">
                <s:conversationPropagation type="end"/>
                </h:commandButton>  
                          			  
            <h:commandButton id="update" 
                          value="#{messages.save}b" 
                         action="#{postHome.update}"
                       rendered="#{postHome.managed}">                       
                <s:conversationPropagation type="end"/>
                </h:commandButton>
                        			  
            <h:commandButton id="delete" 
                          value="#{messages.delete}" 
                         action="#{postHome.remove}"
                       rendered="#{postHome.managed}">
                <s:conversationPropagation type="end"/>
                </h:commandButton>
                    
            <s:button id="done" 
                   value="#{messages.done}"
             propagation="end"
                    view="/Post.xhtml"
                rendered="#{postHome.managed}"/>
                
            <s:button id="cancel" 
                   value="#{messages.cancel}"
             propagation="end"
                    view="/#{empty postFrom ? 'TopicList' : postFrom}.xhtml"
                rendered="#{!postHome.managed}"/>
                
        </div>
        
    </h:form>
</ui:define>

</ui:composition>

Never mind.... the solution in my case was to change the conversation propagation settings (to join, which is what I use in other places in the application). Now I'm sufficiently new to Seam to say that I don't know why the difference, but the important thing is that it works :).