I'm encountering a very weird issue, only in GNU/Linux.

Consider the following gist that shows an open dialog and presents the resulting filename in the screen: https://gist.github.com/jviotti/b8358165f1694228fbc31e400dbadab6, which you can run by `npm install && npm start`.

Now create a file with a `.img.gz` extension, like `foo.img.gz`. Using the `touch` command is enough.

Try to select it using the gist application. The `.img.gz` extension is replaced by `.zip` (or whatever is the first item of the extensions filter) for some strange reason.

The issue only seems reproducible with files containing multiple extensions, and when a dialog filter is present.
- Electron version: 1.2.5
- Operating system: GNU/Linux (Ubuntu 14.04 and Arch Linux)

atom/browser/ui/file_dialog_gtk.cc
const std::string& title,
                    const std::string& button_label,
                    const base::FilePath& default_path,
                    const Filters& filters,
                    base::FilePath* path) {
  FileChooserDialog save_dialog(GTK_FILE_CHOOSER_ACTION_SAVE, parent_window,
                                title, button_label, default_path, filters);
  gtk_widget_show_all(save_dialog.dialog());
  int response = gtk_dialog_run(GTK_DIALOG(save_dialog.dialog()));
  if (response == GTK_RESPONSE_ACCEPT) {
    *path = save_dialog.GetFileName();
    return true;
  } else {
    return false;
  }
}
void ShowSaveDialog(atom::NativeWindow* parent_window,
                    const std::string& title,
                    const std::string& button_label,
                    const base::FilePath& default_path,
                    const Filters& filters,
                    const SaveDialogCallback& callback) {
  FileChooserDialog* save_dialog = new FileChooserDialog(
      GTK_FILE_CHOOSER_ACTION_SAVE, parent_window, title, button_label,
      default_path, filters);
  save_dialog->RunSaveAsynchronous(callback);
}
}