WndProc error

[InertiaM]

Stripped down code :-

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        Select Case m.Msg
            Case WM_SYSCOMMAND
                Select Case Convert.ToInt32(m.WParam)
                    Case Else
                        MyBase.WndProc(m)
                End Select
            Case Else
                MyBase.WndProc(m)
        End Select
    End Sub

When it tries to process Convert.ToInt32(m.WParam), I get :-

Unable to cast object of type 'System.IntPtr' to type 'System.IConvertible'.

but if I use m.WParam.ToInt32, it works.

1. Why?

2. Are there any other occasions like this, when I shouldnt be using a Convert. method?

 

[jmcilhinney]

As the error message suggests, only objects that implement the IConvertible interface can be passed to Convert.ToInt32.