Drag'n'drop was broken

[wmjordan]

The point passed to GetActiveTabIndex should be the client coordinate. Thus the corresponding code in TabControlExtra.OnDragOver should be:

var dragPoint = new Point(drgevent.X, drgevent.Y);
var tabPoint = this.PointToScreen(Point.Empty);
dragPoint.Offset(-tabPoint.X, -tabPoint.Y);
if (this.GetActiveTab(dragPoint) == dragTab) {
    return;
}

int insertPoint = this.GetActiveIndex(dragPoint);
if (insertPoint < 0) return;