By default, the OLEDropMode property is exOLEDropNone. Use the AutoDrag property to specify what the control does when the user clicks and drag the items.

Currently, the ExG2antt control supports only manual OLE Drag and Drop operation. Use the Background(exDragDropBefore) property to specify the visual appearance for the dragging items, before painting the items. Use the Background(exDragDropAfter) property to specify the visual appearance for the dragging items, after painting the items. Use the Background(exDragDropList) property to specify the graphic feedback for the item from the cursor, while the OLE drag and drop operation is running. See the OLEStartDrag and OLEDragDrop events for more details about implementing drag and drop operations into the ExG2antt control.

In the /NET Assembly, you have to use the AllowDrop property as explained here:

• https://www.exontrol.com/sg.jsp?content=support/faq/net/#dragdrop