private void Tree_Drop(object sender, DragEventArgs e) { if (!e.Data.GetDataPresent(DataFormats.FileDrop, true)) { return; } var files = e.Data.GetData(DataFormats.FileDrop, true) as string[]; if (files == null || files.Length == 0) { return; } foreach (var filePath in files) { AppService.AddProjectAssembly(filePath); } e.Handled = true; }