Visual studio 2010 如何实现像avast 9应用程序那样的弹出式面板

如何实现像avast 9应用程序那样的弹出式面板。 我能够实现控件的功能，但问题是使控件保持打开状态，直到鼠标悬停在控制区域之外。 代码是：

 Private Sub btnCourseRegistration_MouseHover(sender As Object, e As EventArgs) Handles btnCourseRegistration.MouseHover
        TabControlSubMenu.Visible = True
        TabControlSubMenu.SelectedTab = TabPageCourseRegistrationSubMenu

    End Sub

    Private Sub btnCourseRegistration_MouseLeave(sender As Object, e As EventArgs) Handles btnCourseRegistration.MouseLeave

        If TabControlSubMenu.Focused = False Then
            TabControlSubMenu.Visible = False
        Else
            TabControlSubMenu.Visible = True
        End If
    End Sub

    Private Sub TabControlSubMenu_MouseLeave(sender As Object, e As EventArgs) Handles TabControlSubMenu.MouseLeave
        TabControlSubMenu.Visible = False
    End Sub.