var modes = new Array( );
modes[ 0 ] = "Book";
modes[ 1 ] = "Changes";
modes[ 2 ] = "Graph";
modes[ 3 ] = "Downloads";
modes[ 4 ] = "Options";
modes[ 5 ] = "Help";

function changeMode( mode ) {
  var success = true;
  if( mode == "Downloads" ) success = top.showDownloads( );
  else if( mode == "Graph" ) success = top.showGraph( );
  else if( mode == "Changes" ) success = top.showChanges( );
  else if( mode == "Book" ) success = top.showBook( );
  else if( mode == "Options" ) success = top.showOptions( );
  else if( mode == "Help" ) success = top.showHelp( );
  else {
    alert( "Unexpected menu item: \"" + mode + "\"" );
    success = false;
  }

  if( success ) setMode( mode );
  return success;
}

function setMode( mode ) {
  if( document.getElementById ) {
    for( var i = 0; i < document.menu.elements.length; ++i ) {
      if( document.menu.elements[ i ].value == mode ) {
	document.getElementById( mode ).setAttribute( "class", "active" );
      }
      else {
	document.getElementById( document.menu.elements[ i ].value ).setAttribute( "class", "inactive" );
      }
    }
  }
}

function checkMode( ) {
  setMode( modes[ top.getMode( ) ] );
}
  
setInterval( checkMode, 1000 );