private DesignFile open_dialog(Stat stat,String p_design_dir_name){
  JFileChooser file_chooser=new JFileChooser(p_design_dir_name);
  FileFilter file_filter=new FileFilter(DesignFile.all_file_extensions);
  file_chooser.setFileFilter(file_filter);
  file_chooser.showOpenDialog(null);
  File curr_design_file=file_chooser.getSelectedFile();
  if (curr_design_file == null)   return null;
  return new DesignFile(stat,curr_design_file,file_chooser);
}

private DesignFile open_dialog ( Stat stat , String p_design_dir_name ) { JFileChooser file_chooser = new JFileChooser ( p_design_dir_name ) ; FileFilter file_filter = new FileFilter ( DesignFile . all_file_extensions ) ; file_chooser . setFileFilter ( file_filter ) ; file_chooser . showOpenDialog ( null ) ; File curr_design_file = file_chooser . getSelectedFile ( ) ; if ( curr_design_file == null ) return null ; return new DesignFile ( stat , curr_design_file , file_chooser ) ; }
shows a file chooser for opening a design file
