function pushdown( name, name2 ) {

	var saveCurrent = currentDown;
	var saveCurrent2 = currentDown2;
	currentDown = name;
	currentDown2 = name2;

	if( saveCurrent ) {
		turnoff( saveCurrent );
	}
	if( saveCurrent2 ) {
		turnoff( saveCurrent2 );
	}

	if( name ) {
		lightup( name );
	}
	if( name2 ) {
		lightup( name2 );
	}
}

function lightup( name ) {	
	var button = userInterface.getButton( name );

	if( button ) {
		document[ name ].src = button.onState.src;
	}
}

function turnoff( name ) {
	if( !( currentDown == name || currentDown2 == name ) ) {
		var button = userInterface.getButton( name );

		if( button ) {
			document[ name ].src = button.offState.src;
		}
	}
}

var currentDown;
var currentDown2;
var userInterface = new Buttons();
var browser = new Browser();