The OnDragDrop method is a virtual method in the Editor.GameObjectControlWidget class. It is designed to handle drag-and-drop events when a drag operation is completed and the dragged item is dropped onto the widget. This method is part of the drag-and-drop event handling mechanism in the editor environment.

To use the OnDragDrop method, you should override it in a subclass of GameObjectControlWidget if you need to provide custom behavior when a drag-and-drop operation is completed. The method takes a single parameter of type Editor.Widget/DragEvent, which contains information about the drag event, such as the source and target of the drag operation.

Here is how you might override this method:

public class MyCustomWidget : GameObjectControlWidget
{
    public override void OnDragDrop(Editor.Widget.DragEvent ev)
    {
        // Custom logic for handling the drag-drop event
        if (ev != null)
        {
            // Process the drag event
            // For example, add the dragged object to a list or update the UI
        }
    }
}