Ok, here's my findings.

I created a temp version of Tables:

    Public Class TablesTemp
        Inherits System.Collections.Specialized.NameObjectCollectionBase

        Public Overloads Sub Add(ByVal Table As Table)
            BaseAdd(Table.Name, Table)
        End Sub

        Default Public Overloads ReadOnly Property Item(ByVal Title As String) As Table
            Get
                Return CType(BaseGet(Title), Table)
            End Get
        End Property

        Default Public Overloads ReadOnly Property Item(ByVal Index As Integer) As Table
            Get
                Return CType(BaseGet(Index), Table)
            End Get
        End Property

        ' Removes an entry with the specified key from the collection
        Public Sub Remove(ByVal tcKey As String)
            BaseRemove(tcKey)
        End Sub

        ' Removes an entry in the specified index from the collection
        Public Sub Remove(ByVal tnIndex As Integer)
            BaseRemoveAt(tnIndex)
        End Sub

        ' Removes everything
        Public Sub Clear()
            BaseClear()
        End Sub

    End Class

Then, I tried:

oApp.Tables = oApp.TablesTemp

This does not work as the designer is complaining:

"Value of type 'Framework.Framework.TablesTemp' cannot be converted to 'Framework.Framework.Tables'. "

So, I thought we are not able to assign a NameObjectCollectionBase object as is to another one. So, I implemented a cloneable interface to TablesTemp. I got:

"Unable to cast object of type 'Framework.Framework.TablesTemp' to type 'Framework.Framework.Tables'."

So, is this normal we cannot assign a NameObjectCollectionBase object to another one?