Use the PopupOpened event - something like this:

Public Class NominalPaymentReceiptForm
    'alter grid and popup columns
    Sub New(ByVal form As AmendableForm)
        Dim grid As Grid
        grid = CType(form.FindControlByName("nominalGrid").UnderlyingControl, Grid)
        grid.Columns(0).Width += 20
        grid.Columns(1).Width -= 10
        grid.Columns(2).Width -= 10
        grid.Columns(3).Width += 20
        grid.Columns(3).AutoSize = True
        Dim nominalGridLookup As Sage.MMS.Controls.NominalGridLookup
        nominalGridLookup = CType(form.FindControlByName("nominalGridLookup").UnderlyingControl, Sage.MMS.Controls.NominalGridLookup)
        AddHandler nominalGridLookup.PopupOpened, AddressOf NominalGridLookup_PopupOpened
    End Sub
    Private Sub NominalGridLookup_PopupOpened(ByVal sender As Object, ByVal args As Sage.Common.Controls.PopupOpenedEventArgs)
        If args.InvokeType = Sage.Common.Controls.InvokeType.Validate Then Exit Sub
        Dim list As List = CType(args.Form.Controls(0), List)
        list.Columns(0).Width = 70
        list.Columns(1).Width = 25
        list.Columns(2).Width = 25
        list.Columns(3).Width = 200
        list.Columns(4).Width = 50
    End Sub
End Class

By the way, are you aware of the Developers' forum? May be a better place for development queries like this - and rumour has it that development support may even look at it once in a while!

thank you. I will have a look at the site. last time I went there no one answer my question so I thought the site is not active.

thank you. I will have a look at the site. last time I went there no one answer my question so I thought the site is not active.