ASPxClientGanttTimeTooltipShowingEventArgs Class

<dx:ASPxGantt ID="Gantt" >
    <ClientSideEvents TaskUpdating="function(s, e) {
        var customContainer = document.createElement("div");  
        customContainer.classList.add("custom-time");
        customContainer.textContent = 'End Date: ' + e.item.end;  
        e.container.appendChild(customContainer); 
    }" />
</dx:ASPxGantt>

@Html.DevExpress().Gantt(settings => {
    settings.Name = "gantt";
    settings.ClientSideEvents.TaskUpdating = "function (s, e) { 
        var customContainer = document.createElement("div");  
        customContainer.classList.add("custom-time");
        customContainer.textContent = 'End Date: ' + e.item.end;  
        e.container.appendChild(customContainer); 
    }";
    ...
}).Bind(
    GanttDataProvider.Tasks, GanttDataProvider.Dependencies, 
    GanttDataProvider.Resources, GanttDataProvider.ResourceAssignments
).GetHtml()