In your code, you are using UpdateUI function which is asynchronous and trying to set the combo to the newly added item. Since UpdateUI function is asynchronous, it will take some time to update the UI to relfect the changes. You will need to set some timeout to wait for the WebCombo to refresh. Here is the modified snippet:

var currentItemResourceCount;

function wbSave_OnClick() {    var wr = ISGetObject("wcResources");    //create and add a new resource if one is not selected (an existing event)
    if (wr.Value == "") {
        currentItemResourceCount = wr.Rows.length;
        
        ISGetObject("wiResourceName").SetValueData("New Resource1");
        ISGetObject("wcResourcesColor").SetSelectedIndex(0);
        ISGetObject("wiRLocation").SetValueData("N/A");
        ISGetObject("wiRDescription").SetValueData("New Resource1");
        WS_OnSaveResource();
        //Now select the new row
        wr.UpdateUI();
        SetLatestResource();
    }
    //Now call original function and return
    WS_OnSave();
    return true;
}
function SetLatestResource() {
    var wr = ISGetObject("wcResources");
    if (wr.Rows[currentItemResourceCount] != null) {
        ISGetObject("wcResources").Rows[wr.Rows.length - 1].Select();
    }
    else {
        setTimeout(function() { SetLatestResource(); }, 10);
    }
}

Glenn,

   Well that makes sense! I did not realize that was asynchronous. I made some slight changes, to call the original function only after the resource is set in the timeout function, or otherwise only if the resource is already selected.

var currentItemResourceCount;

function wbSave_OnClick() {
    var wr = ISGetObject("wcResources");

    //create and add a new resource if one is not selected (an existing event)
    if (wr.Value == "") {
        currentItemResourceCount = wr.Rows.length;
        ISGetObject("wiResourceName").SetValueData("New Resource");
        ISGetObject("wcResourcesColor").SetSelectedIndex(0);
        ISGetObject("wiRLocation").SetValueData("N/A");
        ISGetObject("wiRDescription").SetValueData("New Resource");
        WS_OnSaveResource();

        wr.UpdateUI();
        SetLatestResource();
    } else
        WS_OnSave();

    return true;
}

function SetLatestResource() {
    var wr = ISGetObject("wcResources");
    if (wr.Rows[currentItemResourceCount] != null) {
        //Now select the new row
        ISGetObject("wcResources").Rows[wr.Rows.length - 1].Select();

        //call original function
        WS_OnSave();
    }
    else {
        setTimeout(function() { SetLatestResource(); }, 10);
    }
}

Thanks so much for your help. It is really great to have this kind of flexibility with your control.