internal void TestDrop(IDockDragSource dragSource, DockOutlineBase dockOutline) { if (!dragSource.CanDockTo(this)) { return; } Point ptMouse = Control.MousePosition; HitTestResult hitTestResult = 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); } }