I have resolved the issue myself, but not sure whether it's the best.

In beforeShowForm event, we can do initialize the editing form.

for example hide certain fields:

        $('#tr_spentTrigger', formId).hide();
        $('#tr_freqTrigger', formId).hide();
and dynamicly hide/show fields:

$('#rewardType', formId).change(function(){
            var index = $(this)[0].selectedIndex;
            console.log("reward type selected" + ", selcted index: " + index);
            if (index == 4) {
                $('#tr_freqTrigger', formId).show();
                $('#tr_spentTrigger', formId).hide();
            }
            else
                if (index == 5) {
                    $('#tr_spentTrigger', formId).show();
                    $('#tr_freqTrigger', formId).hide();
                }
                else {
                    $('#tr_spentTrigger', formId).hide();
                    $('#tr_freqTrigger', formId).hide();
                }
        });

where formId is the edit form.

Burt

I found in documentation an example on CheckInvoice where you can do dynamic editing forms. However, I just can't figure out where this CheckInvoice function should be hooked with?

in editrules? How?

function CheckInvoice(formid) { var invno = 'invoice=' + $("#invoice",formid).val() ; if (invno == 'invoice=') { alert("invoice is blank; please enter account #") } else { $.getJSON(searchinvoice, invno, function(data) { if (data.status == 'No match found; please try again') { alert(data.status) } else { // Load the fields we know about $("#invoiced",formid).val(data.invoiced); $("#outstanding",formid).val(data.os); $("#acctname",formid).val(data.account); $("#project",formid).val(data.project); // Disabled loaded fields $("#acctname",formid).attr('disabled',true); $("#project",formid).attr('disabled',true); // Hide unneeded fields $("#tr_comment",formid).hide(); $("#tr_projectnumber",formid).hide(); $("#tr_shorttitle",formid).hide(); $("#tr_client",formid).hide();

Regards,

Burt