Allow form to be moved only with a right click

Ive created a button inside of a form that calls an exe using the process command.  This button is going to be placed on a touch screen so I want to be able to move it only with right click.  So far i've got it where it will move with any click. Im very new at using Visual so any help will be greatly appreciated.

Heres what ive got so far:

Public Class Form1
    'Declare the variables
    Dim drag As Boolean
    Dim mousex As Integer
    Dim mousey As Integer
    Dim blnDrag As Boolean

    Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseDown
        drag = True 'Sets the variable drag to true.
        mousex = Windows.Forms.Cursor.Position.X - Me.Left 'Sets variable mousex
        mousey = Windows.Forms.Cursor.Position.Y - Me.Top 'Sets variable mousey
    End Sub

    Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseMove
        'If drag is set to true then move the form accordingly.
        If drag Then
            Me.Top = Windows.Forms.Cursor.Position.Y - mousey
            Me.Left = Windows.Forms.Cursor.Position.X - mousex
        End If
    End Sub

    Private Sub Form1_MouseUp(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseUp
        drag = False 'Sets drag to false, so the form does not move according to the code in MouseMove
    End Sub


    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Process.Start("C:\Program Files (x86)\.exe location")
    End Sub

End Class