label控件可以用鼠标拖动，但没有边界，附代码，请老师们给点意见如何定义边界～～～～～

Public Class tftest
    Dim ss As Boolean
    Dim mov As Point
    Private Sub Label1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label1.MouseDown
        ss = True
        mov = New Point(e.X, e.Y)
    End Sub

    Private Sub Label1_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label1.MouseUp
        ss = False
    End Sub

    Private Sub Label1_MouseMove(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Label1.MouseMove
        Dim a, b As Integer
        a = mov.X - e.X
        b = mov.Y - e.Y
        TextBox1.Text = a
        TextBox2.Text = b
        If ss = True And Me.Label1.Left >= 10 And Me.Label1.Left < Me.Width - Me.Label1.Width Then
            Me.Label1.Left = Me.Label1.Left - a
        End If
        If ss = True And Me.Label1.Top > 0 And Me.Label1.Top < Me.Height - Me.Label1.Height Then
            Me.Label1.Top = Me.Label1.Top - b
        End If
    End Sub
    Private Sub Label1_Move(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Move
        If Me.Label1.Left < 10 Then
            Me.Label1.Left = 10
        End If
    End Sub
End Class

以上是代码，实现label用鼠标在窗体上拖动，但问题是目前代码不能产生边界，设置了边界范围，但还是可以拖出去。如果用label1_move这个事情中的代码，可以实现边界，但当控件拖出边界的范围时，会出现花屏现像。如下：

[解决办法]
自己搞定了~~~