The issue has been discussed further in Live Chat. Since the goal is to modify the ability to enable or disable edit of a row or cell, using client side event handler OnAfterInitialize is possible to achieve such feature.

The client side function to disable edit is SetForceNoEdit(true), which could be applied to WebGrid cell object or WebGrid row object. Here is the snippet to disable first row in WebGrid and column Author in second row of WebGrid:

grid.RootTable.GetRow(0).SetForceNoEdit(true);

grid.RootTable.GetRow(1).GetCell('Author').SetForceNoEdit(true);

Such behavior also occur in our test, I have create a note to discuss this issue further with the developer regarding the expected behavior under such condition.

In the mean time, if you would like the newly created event for unselected resource to be hidden after an add operation, you coud invoke the refresh method during OnAfterAdd WebScheduler client side event:

function WebScheduler1_OnAfterAdd(ctrlId)
{
    setTimeout(function()
    {
        var sched = ISGetObject(ctrlId);
        sched.Refresh();
    }, 500);
}

You coud use the OnEditorContextMenu client side event handler for such scenario as detailed in WebTextEditor documentation on the article "How-to: Add Item in Context Menu"

Here is the snippet for your scenario:

function WebTextEditor1_OnEditorContextMenu(controlId, menuObj)
{            
    var items = menuObj.RootMenu.Items;
    if (items.GetNamedItem("vCustom") == null)            
    {
        items.Add(new WebMenuSeparatorItem());
        var vCustomItem = new WebMenuItem("vCustom", "vCustomer", null, OnClickItemContext)

        vCustomItem.Items.Add(new WebMenuItem("vcFirstName", "FirstName", null, OnClickItemContext));
        vCustomItem.Items.Add(new WebMenuItem("vcLastName", "LastName", null, OnClickItemContext));
        vCustomItem.Items.Add(new WebMenuItem("vcAddress", "Address", null, OnClickItemContext));
        vCustomItem.Items.Add(new WebMenuItem("vcPhone", "Phone", null, OnClickItemContext));

        items.Add(vCustomItem);
    }
}

function OnClickItemContext(menuItem)
{
    var rte = ISGetObject("WebTextEditor1");

    var keyword = {
        vcFirstName: "vCustomer.FirstName",
        vcLastName: "vCustomer.LastName",
        vcAddress: "vCustomer.Address",
        vcPhone: "vCustomer.Phone"
    };

    setTimeout(function()
    {
        rte.SetValueToCurrentPosition(keyword[menuItem.Name]);
    }, 500);
}

The fix is still being analyze as the issue is still open. In the meantime, as a workaround you could try invoking a client script event in order to modify the input forecolor on the server side.

Here is the snippet of the client side function, setting the forecolor is done by adding a new css class which has the style you wish to add:

<style type="text/css">
.RedText
{
    color: Red !important;
}
</style>
<script type="text/javascript" language="javascript">
    function SetColor()
    {
        var input = ISGetObject('WebInput1');

        input.GetControlElement().className += " RedText";
    }
</script>

The server side function to invoke the SetColor function:

Page.ClientScript.RegisterStartupScript(this.GetType(), "SetColor", "<script>SetColor();</script>");

If you do not define the child table, during PrepareDataBinding WebGrid event handler you will need to create the child table and child table column structure and reset the hierarchical property under LayoutSettings.

Here is the snippet for the PrepareDataBinding event for the sent sample with your scenario applied:

protected void WebGrid1_PrepareDataBinding(object sender, ISNet.WebUI.WebGrid.DataSourceEventArgs e)
{
    if(!Page.IsPostBack)
    {
        WebGrid1.RootTable.ChildTables.Add("Order");

        WebGridTable orderTbl = WebGrid1.RootTable.ChildTables[0];
        orderTbl.DataMember = "Order";
        orderTbl.Columns.AddRange(new WebGridColumn[] { 
            new WebGridColumn("OrderID","OrderID","OrderID"),
            new WebGridColumn("CustomerID","CustomerID","CustomerID"),
            new WebGridColumn("OrderName","OrderName","Name"),
            new WebGridColumn("OrderQuantity","OrderQuantity","Quantity"),
        });
    }
    
    WebGrid1.LayoutSettings.Hierarchical = true;
}

The WebGrid RootTable definition:

<RootTable DataMember="Customer" DataKeyField="CustomerID">
    <Columns>
        <ISWebGrid:WebGridColumn DataMember="CustomerID" Name="ID"></ISWebGrid:WebGridColumn>
        <ISWebGrid:WebGridColumn DataMember="CustomerName" Name="Name"></ISWebGrid:WebGridColumn>
        <ISWebGrid:WebGridColumn DataMember="CustomerAddress" Name="Address"></ISWebGrid:WebGridColumn>
    </Columns>
</RootTable>