DropDownButton下拉菜单位置问题vb.net

[rmini]

通常下拉菜单是在DropDownButton1的下方，我的意思是如果窗体变化时，DropDownButton1在窗体底部时，DropDownButton1的底部至屏幕底部之间显示不了菜单，菜单则显示在DropDownButton1的上方，以下是我的代码，有点问题，一是点击下拉箭头时下拉菜单在屏幕最左上角仿佛有闪一下的感觉，二是位置还是有点不对，望各位高人给以指点(DropDownButton1绑定菜单ContextMenuStrip1)

Private Sub DropDownButton1_ArrowButtonClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles DropDownButton1.ArrowButtonClick
ContextMenuStrip1.Show()
If My.Computer.Screen.Bounds.Bottom.ToString - Me.PointToScreen(DropDownButton1.Location).Y > Me.ContextMenuStrip1.Height Then
Me.ContextMenuStrip1.Left = Me.PointToScreen(DropDownButton1.Location).X
Me.ContextMenuStrip1.Top = Me.PointToScreen(DropDownButton1.Location).Y + Me.DropDownButton1.Height
Else
Me.ContextMenuStrip1.Left = Me.PointToScreen(DropDownButton1.Location).X
Me.ContextMenuStrip1.Top = Me.PointToScreen(DropDownButton1.Location).Y - ContextMenuStrip1.Height
End If
End Sub

[bw555]

    Private Sub DropDownButton1_ArrowButtonClick(ByVal sender As Object, ByVal e As System.EventArgs) Handles DropDownButton1.ArrowButtonClick
        Dim V_TOP As Single
        If My.Computer.Screen.Bounds.Bottom.ToString - Me.PointToScreen(DropDownButton1.Location).Y > Me.ContextMenuStrip1.Height Then
            V_TOP = Me.DropDownButton1.Height
        Else
            V_TOP = -ContextMenuStrip1.Height
        End If
        ContextMenuStrip1.Show(Me.DropDownButton1, 0, V_TOP)
    End Sub

[rmini]

非常谢谢！菜单感觉闪的问题解决了，但是还是有菜单遮住整个DropDownButton1的情况，我的意思是要么菜单都在DropDownButton1的上方，要么都在DropDownButton1的下方

[rmini]

If My.Computer.Screen.WorkingArea.Height - Me.PointToScreen(DropDownButton1.Location).Y - Me.DropDownButton1.Height > Me.ContextMenuStrip1.Height Then

非常谢谢bw555