Hello,
I think the only way to select an element is:
You must filter the datatable according to its definition, in my case I have a column called "pk".
Then select all the elements (filtered)
And finally put back the original items.
Dim tmp As DataTable = MultiSelectionComboBox1.DataSource()
MultiSelectionComboBox1.DataSource = CType(Me.DataSource, DataTable).Select("pk=2").CopyToDataTable
MultiSelectionComboBox1.SelectAll()
MultiSelectionComboBox1.DataSource = tmp