Private Sub btnAddFile_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAddFile.Click
        Dim doc As Document = ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim ed As Editor = doc.Editor
        Dim acDoc As Document = ApplicationServices.Application.DocumentManager.MdiActiveDocument
        Dim strDWGName As String
        Dim strFolderPath As String
        Dim strListboxName As String = Nothing

        Try
            If TreeView1.SelectedNode Is Nothing Then ' nothing sleected for folder 
                MsgBox("Select a folder first (node in the tree)")
                Exit Sub
            End If

            Dim diaSave As New ProjectsSaveCurrentDWG() ' Make new empty object of dialog box

            strFolderPath = TreeView1.SelectedNode.Tag.ToString

            'If it's needed add a "\" to the path
            If Not strFolderPath.Substring(strFolderPath.Length - 1) = "\" Then
                strFolderPath = strFolderPath + "\"
            End If

            diaSave.tboFolder.Text = strFolderPath

            diaSave.tboName.Text = System.IO.Path.GetFileNameWithoutExtension(acDoc.Name)

            If diaSave.ShowDialog() = DialogResult.OK Then
                'Check if valid filename
                If diaSave.tboName.Text = "" Then
                    MsgBox("You failed to enter a file name!")
                    Exit Sub
                End If
                If FilenameIsOK(strFolderPath + diaSave.tboName.Text) Then
                    'Valid filename entered
                    Dim obj As Object = ApplicationServices.Application.GetSystemVariable("DWGTITLED")

                    strDWGName = strFolderPath + diaSave.tboName.Text
                    strListboxName = diaSave.tboName.Text 'Used to add file to listbox
                    '' Save the active drawing
                    acDoc.Database.SaveAs(strDWGName, True, DwgVersion.Current, _
                                          acDoc.Database.SecurityParameters)

                Else
                    MsgBox(diaSave.tboName.Text + vbCrLf + " You entered an invalid file name!")
                    Exit Sub
                End If
            End If

            'Add to listbox
            ListBox1.Items.Add(strListboxName + ".dwg")


        Catch ex As System.Exception
            ed.WriteMessage(vbLf & "Exception during btnAddFile_Click: {0}", ex.Message)
        End Try

    End Sub ' Saves current DWG into current Tree Node directory