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,
                    int properties,
                    std::vector<base::FilePath>* paths) {
  GtkFileChooserAction action = GTK_FILE_CHOOSER_ACTION_OPEN;
  if (properties & FILE_DIALOG_OPEN_DIRECTORY)
    action = GTK_FILE_CHOOSER_ACTION_SELECT_FOLDER;
  FileChooserDialog open_dialog(action, parent_window, title, button_label,
                                default_path, filters);
  if (properties & FILE_DIALOG_MULTI_SELECTIONS)
    gtk_file_chooser_set_select_multiple(GTK_FILE_CHOOSER(open_dialog.dialog()),
                                         TRUE);
  gtk_widget_show_all(open_dialog.dialog());
  int response = gtk_dialog_run(GTK_DIALOG(open_dialog.dialog()));
  if (response == GTK_RESPONSE_ACCEPT) {
    *paths = open_dialog.GetFileNames();
    return true;
  } else {
    return false;
  }
}
void ShowOpenDialog(atom::NativeWindow* parent_window,