Private Sub Start_Click(sender As System.Object, e As System.EventArgs) _
   Handles Start.Click
RemoveHandler MouseClick, AddressOf Start.Click
        System.Threading.Thread.Sleep(2000)
End Sub

Private Structure NativeMessage
    Public handle As IntPtr
    Public msg As UInteger
    Public wParam As IntPtr
    Public lParam As IntPtr
    Public time As UInteger
    Public p As System.Drawing.Point
End Structure
Private Declare Auto Function PeekMessage Lib "user32.dll" ( _
    _
    ByRef lpMsg As NativeMessage, _
    ByVal hWnd As IntPtr, _
    ByVal wMsgFilterMin As UInteger, _
    ByVal wMsgFilterMax As UInteger, _
    ByVal flags As UInteger _
) As Boolean
Private Const WM_MOUSEFIRST As UInteger = &H200
Private Const WM_MOUSELAST As UInteger = &H20D
Private Const PM_REMOVE As Integer = &H1
 
' Flush all pending mouse events.
Private Sub FlushMouseMessages()
    Dim msg As NativeMessage
    ' Repeat until PeekMessage returns false.
    While (PeekMessage(msg, IntPtr.Zero, WM_MOUSEFIRST, _
        WM_MOUSELAST, PM_REMOVE))
 
    End While
End Sub