Warn by leaving a form view with unsaved changes

Question

Hello JSF / Richfaces users,
maybe that's not the first time, that someone asks this question here, but unfortunately I couldn't found any concrete examples on the forum. So I'd like really to get your help:
I'd like to put some "input listeners" on my form views, so that when the user makes changes (typing in inputText, selection another value in selectMenu or checking a Checkbox), then he clicks on another Button / Link without saving, he shoudl will be warned by a dialog box remebering him to save the changes or leaving the view without saving (changes will be lost).
I tried at first to put a boolean "inputChanged" on my Bean, then setting it to true with an adapted event (onchange) by each component. And by the buttons/links which link to another page I tried to show a <rich:modalpanel> once the value of "inputChanged" is true but I couldn't realize this conditions.
Thereafter I found a solution based on Javascript:
<script language="javascript" type="text/javascript">
    // Keep flag when something had changed
    var changed = false;
    Save in "changed" flag, whether an input had been done by the user.
    after that the calling of this method will be removed
    from the corresponding attribute of the input elements,
    in order to avoid redundant method calls */
    function storeChange(aChanged, aElement) {
        changed = aChanged;
        aElement.setAttribute('onchange', '');
    Finally and when the "changed" flag is true, a confirmation message will be shown
    to confirm whether the page could be left.  
    window.onbeforeunload=function unloadAlert() {
        if(changed) {
            return 'You have unsaved changes on the page. If you click on OK, the changes will be lost';
        return null;
</script>{code}
And in the view:
{code}<a4j:form>
        <h:outputLabel id="label_name" value="Name" for="in_name" />
        <h:inputText id="in_name" value="#{bean.name}"
            onchange="storeChange(true, this)" />
        <br />
        <h:outputLabel id="label_email" value="E-Mail" for="in_email" />
        <h:inputText id="in_email" value="#{bean.email}"
            onchange="storeChange(true, this)" />
        <br />
        <a4j:commandButton oncomplete="javascript:changed=false"
            value="Save" />
    </a4j:form>{code}
And now I'd
like rather than the JS terriying dialog box, a user-friendly rich:modalPanel which should do the same function.
For any
indication I will be very very thankful                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           

Answer 1

Hi David,
Thank for the prompt answer. I've tried that before but I have put that in checkin action. So that didn't work before but now as per your suggestion it works nicely. The form isn't evaluated.
However, this time my changes aren't reflected on the user.. Basically what I do is
- checkout user view (with empty form) (in an activity)
- update user view (in another activity)
- check in user view (in another activity)
however, changes are discarded. I used winmerge to compare and saw exactly the necessary fields are updated after update activity. but after checkin no changes are reflected. so what should I do now :(
Relevant actions are:
<Action id='0' application='com.waveset.session.WorkflowServices'>
          <Argument name='op' value='checkoutView'/>
          <Argument name='viewId'>
            <concat>
              <s>User:</s>
              <ref>accountId</ref>
            </concat>
          </Argument>
          <Argument name='type' value='User'/>
          <Argument name='id' value='$(accountId)'/>
          <Argument name='Form' value='Empty Form' />
          <Return from='view' to='user'/>
          <Return from='WF_ACTION_ERROR' to='error'/>
        </Action>
        <Action id='0' application='com.waveset.session.WorkflowServices'>
          <Argument name='op' value='checkinView'/>
          <Argument name='view' value='$(user)'/>
          <Return from='WF_ACTION_ERROR' to='error'/>
        </Action>