如何判断鼠标是否位于顶级窗口上方?

WindowFromPoint

[DllImport("user32.dll")]
static extern IntPtr WindowFromPoint(POINT Point);

POINT System.Drawing.Point a declaration for POINT that includes an implicit conversion between the two

GetCursorPos

[DllImport("user32.dll")]
static extern bool GetCursorPos(out POINT lpPoint);

GetParent

[DllImport("user32.dll", ExactSpelling=true, CharSet=CharSet.Auto)]
public static extern IntPtr GetParent(IntPtr hWnd);

    private void timer1_Tick(object sender, EventArgs e) {
        var hdl = WindowFromPoint(Control.MousePosition);
        var ctl = Control.FromHandle(hdl);
        if (ctl != null) {
            var rel = ctl.PointToClient(Control.MousePosition);
            if (ctl.ClientRectangle.Contains(rel)) {
                Console.WriteLine("Found {0}", ctl.Name);
                return;
            }
        }
        Console.WriteLine("No match");
    }

    [System.Runtime.InteropServices.DllImport("user32.dll")]
    private static extern IntPtr WindowFromPoint(Point loc);