public void FileOpenInCollectionAndWindow()
        {
            FlowDocumentBox doc = FileSystemDialogMethods.FileOpenFlowDoc();

            if (!doc.DocumentPathInFileSystem.Equals(String.Empty))
            {
                FlowDocumentBox inCollectionExist = null;
                foreach (FlowDocumentBox box in FlowDocumentsBoxes)
                {
                    if (box.DocumentPathInFileSystem.Equals(doc.DocumentPathInFileSystem))
                    {
                        inCollectionExist = box;
                        break;
                    }
                }
                if (inCollectionExist == null)
                {
                    FlowDocumentsBoxes.Add(doc);
                    SelectedDocumentBox = doc;
                }
                else
                {
                    SelectedDocumentBox = inCollectionExist;
                }
            }
        }
        public void FileNewInCollectionAndWindow()
        {
            FlowDocumentBox newDoc = new FlowDocumentBox(new FlowDocument(), "NewFile");

            FlowDocumentsBoxes.Add(newDoc);
            SelectedDocumentBox = newDoc;
        }