DayPilot Lite for ASP.NET WebForms 3.2 (open-source) introduces Gantt chart and header columns with support for drag&drop resizing.
Additional header columns can be defined using HeaderColumns property. You can define the default columns titles and widths. Columns sizes can be changed by dragging the separator.
Switch to the Gantt mode using ViewType="Gantt". This mode will display each event on a separate row. The rows will be generated automatically from the event set. The order of events in Gantt mode is not changed - it will keep the order supplied in DataSource.
The Gantt mode supports multiple columns for displaying additional data, like task start, task end, task duration and assigned resource. The column HTML is fully customizable using BeforeResHeaderRender event.
See all online demos:
You can download the full source code here: