/// <summary>
        /// Handle when a file is dragged and dropped onto the PDFView Control
        /// </summary>
        private void PDFViewer_Drop(object sender, DragEventArgs e)
        {
            if (e.Data.GetDataPresent(DataFormats.FileDrop))
            {
                // Note: Assuming only 1 file was dropped
                string[] file_paths = (string[])e.Data.GetData(DataFormats.FileDrop);

                if (file_paths.Length > 0)
                {
                    // Let's only handle the first file dropped
                    string file_path = file_paths[0];

                    if (System.IO.Path.GetExtension(file_path) != ".pdf")
                    {
                        return;
                    }

                    PDFDoc doc = new PDFDoc(file_path);
                    PDFViewer.SetDoc(doc);
                }
            }
        }