To aviod the drawing of the drop rectangle, override OnDragOver and do nothing. You would also have to override OnDragEnter and set the DrawEventArgs.Effect to the proper value if your data was present.
public class MyGridControl : GridControl
{
protected override void OnDragDrop(DragEventArgs drgevent)
{
Console.WriteLine("MyGridControl.OnDragDrop");
}
protected override void OnDragOver(DragEventArgs drgevent)
{
//do nothing
}
protected override void OnDragEnter(DragEventArgs drgevent)
{
if(drgevent.Data.GetDataPresent(DataFormats.Text))
drgevent.Effect = DragDropEffects.Move; //maybe Copy?
else
drgevent.Effect = DragDropEffects.None;
}
}