internal void TestDrop(IDockDragSource dragSource, DockOutlineBase dockOutline)
{
if (!dragSource.CanDockTo(this))
return;
Point ptMouse = MousePosition;
HitTestResult hitTestResult = this.GetHitTest(ptMouse);
if (hitTestResult.HitArea == HitTestArea.Caption)
dockOutline.Show(this, -1);
else if (hitTestResult.HitArea == HitTestArea.TabStrip && hitTestResult.Index != -1)
dockOutline.Show(this, hitTestResult.Index);
}