private void SetOutline(DockPane pane, DockStyle dock, int contentIndex) { if (dock != DockStyle.Fill) { Rectangle rect = pane.DisplayingRectangle; if (dock == DockStyle.Right) { rect.X += rect.Width / 2; } if (dock == DockStyle.Bottom) { rect.Y += rect.Height / 2; } if (dock == DockStyle.Left || dock == DockStyle.Right) { rect.Width -= rect.Width / 2; } if (dock == DockStyle.Top || dock == DockStyle.Bottom) { rect.Height -= rect.Height / 2; } rect.Location = pane.PointToScreen(rect.Location); SetDragForm(rect); } else if (contentIndex == -1) { Rectangle rect = pane.DisplayingRectangle; rect.Location = pane.PointToScreen(rect.Location); SetDragForm(rect); } else { using (GraphicsPath path = pane.TabStripControl.GetOutline(contentIndex)) { RectangleF rectF = path.GetBounds(); Rectangle rect = new Rectangle((int)rectF.X, (int)rectF.Y, (int)rectF.Width, (int)rectF.Height); using (Matrix matrix = new Matrix(rect, new Point[] { new Point(0, 0), new Point(rect.Width, 0), new Point(0, rect.Height) })) { path.Transform(matrix); } Region region = new Region(path); SetDragForm(rect, region); } } }