if ((currentPt.X > minpt.X) && (currentPt.X < maxpt.X) && (currentPt.Y > minpt.Y) && (currentPt.Y < maxpt.Y))
...{
this.floatWindow.Controls.Remove(this);
this.tsPanel.SuspendLayout();
this.tsPanel.Controls.Add(this);
this.Location = this.tsPanel.PointToClient(currentPt);
this.tsPanel.ResumeLayout();
this.floatWindow.Dispose();
this.floatWindow = null;

}
}

private void MyToolStrip_EndDrag(object sender, EventArgs e)
...{
//判断移出时
if (this.tsPanel == null)
...{
MessageBox.Show("请先设置ToolStripPanel属性");
return;
}
Point endPoint = Cursor.Position;
int openX, openY;
openX = endPoint.X;
openY = endPoint.Y;
Point clientPt = this.tsPanel.Parent.PointToClient(endPoint);
if (clientPt.Y > tsPanel.Height)
...{
ToolStripFloatWindow fw = new ToolStripFloatWindow();
this.tsPanel.Controls.Remove(this);
fw.Controls.Add(this);
this.Left = 0;
this.Top = 0;
this.FloatWindow = fw;
Point newLoc = new Point(openX, openY);
fw.Show();
fw.Location = newLoc;
fw.SetBounds(newLoc.X, newLoc.Y, this.ClientSize.Width, this.ClientSize.Height);
}
}

private void floatWindow_FormClosing(object sender, FormClosingEventArgs e)
...{
e.Cancel = true;
}

private void MyToolStrip_SizeChanged(object sender, EventArgs e)
...{
if (this.isFloating)
...{
this.floatWindow.Width = this.ClientSize.Width;
}
}

#endregion

}
}

结论。 该方法实现较简单， 当不愿意使用功能较强大的第三方控件库时可以采用这种方法，缺点是负责浮动的容器是一个窗口，不大美观。

(编辑:aniston)