if (document.images) {
    webbtup       	= new Image() ;
    webbtup.src   	= "images/but_1.png" ;
    webbtdown    		= new Image() ;
    webbtdown.src 	= "images/but_1_on.png" ;
	
	printbtup			= new Image() ;
	printbtup.src		= "images/but_2.png" ;
	printbtdown		= new Image() ;
	printbtdown.src	= "images/but_2_on.png" ;
	
	drawingbtup			= new Image() ;
	drawingbtup.src		= "images/but_3.png" ;
	drawingbtdown		= new Image() ;
	drawingbtdown.src	= "images/but_3_on.png" ;
	
	artbtup		= new Image() ;
	artbtup.src	= "images/but_4.png" ;
	artbtdown		= new Image() ;
	artbtdown.src	= "images/but_4_on.png" ;
}
function buttondown( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "down.src" );
    }
}
function buttonup ( buttonname )
{
    if (document.images) {
      document[ buttonname ].src = eval( buttonname + "up.src" );
    }
}