private void OnGUI()
    {
        invoiceNumber = EditorGUILayout.TextField("Invoice Number:", invoiceNumber).Trim(' ');
        channel       = (MeshToTerrainUpdateChannel)EditorGUILayout.EnumPopup("Channel:", channel);

        if (GUILayout.Button("Check new versions"))
        {
            CheckNewVersions();
        }

        scrollPosition = EditorGUILayout.BeginScrollView(scrollPosition);

        if (updates != null)
        {
            foreach (MeshToTerrainUpdateItem update in updates)
            {
                update.Draw();
            }
            if (updates.Count == 0)
            {
                GUILayout.Label("No updates");
            }
        }

        EditorGUILayout.EndScrollView();
    }
    private void OnEnable()
    {
        if (EditorPrefs.HasKey("MeshToTerrainInvoiceNumber"))
        {
            invoiceNumber = EditorPrefs.GetString("MeshToTerrainInvoiceNumber");
        }
        else
        {
            invoiceNumber = "";
        }

        if (EditorPrefs.HasKey("MeshToTerrainUpdateChannel"))
        {
            channel = (MeshToTerrainUpdateChannel)EditorPrefs.GetInt("MeshToTerrainUpdateChannel");
        }
        else
        {
            channel = MeshToTerrainUpdateChannel.stable;
        }
    }