function selectPage(page) {
  
    if (document.getElementById('currentPage').value != page) {
    
	    /* for current page */
	    document.getElementById('currentPage').value = page;
	  	
	  	/*for centerImg*/
	    document.getElementById('centerImg').src = "images/lanstead_" + page + ".gif";
	    
	    /* for navegation bar*/
	  	document.getElementById('navegationBarPosition').src = "images/navi_" + page + ".gif";
	
	    if (page != 1 && page != 5) {
	        viewFirstPreview();
	        viewLastNext();
	    } else {
	        if (page == 1){
	            hiddenFirstPreview();
	            viewLastNext();
	        }
	        if (page == 5) {
	            hiddenLastNext();
	            viewFirstPreview();
	        }  
	    }
	    if (page == 4) {
	        document.getElementById('viewAll').style.display = "none";
	        document.getElementById('view4').style.display = "block";
	  	} else {
	        document.getElementById('view4').style.display = "none";
	        document.getElementById('viewAll').style.display = "block";
	    }
    }
}

function hiddenFirstPreview() {
  	document.getElementById('navegationBarFirst').src="images/empty1.gif";
  	document.getElementById('navegationBarPrevious').src="images/empty2.gif";  	
}

function viewFirstPreview() {
  	document.getElementById('navegationBarFirst').src="images/navi_first.gif";
  	document.getElementById('navegationBarPrevious').src="images/navi_previous.gif"; 	
}

function hiddenLastNext() {
    showHide("none");
}

function viewLastNext() {
    showHide("block");
}

function showHide(state) {
    document.getElementById('navegationBarNext').style.display=state;
  	document.getElementById('navegationBarLast').style.display=state;
}

function next() {
    page = document.getElementById('currentPage').value;
    if (page < 5) {
  	    selectPage(parseInt(page) + 1);
    } 
}

function previous() {
    page = document.getElementById('currentPage').value;
    if (page > 1 ) {
  	    selectPage(parseInt(page) - 1);
    } 
}

function lostFocus() {
    if (!window.ActiveXObject) {
        document.getElementById('currentPage').focus();
    }	 
}