var minScrollHeight = 620;

$( document ).ready( function () {
	if($.browser.opera) return;
	
    var pageSize = getPageSize();
    
    if(pageSize[3] >= minScrollHeight) {
        setScrollFollow();
    } else {
        $(window).bind("resize", chkHeight);
    }
} );

function setScrollFollow() {
    $( '#feature_navi' ).scrollFollow( {
        speed: 1300,
        offset: 10,
        onText: 'Disable Follow',
        offText: 'Enable Follow'
    } );
}

function chkHeight() {
    var pageSize = getPageSize();

    if(pageSize[3] >= minScrollHeight) {
        $(window).unbind("resize", chkHeight);
        setScrollFollow();
    }
}

function getPageSize() {
    var xScroll, yScroll;

    if (window.innerHeight && window.scrollMaxY) {
        xScroll = document.body.scrollWidth;
        yScroll = window.innerHeight + window.scrollMaxY;
    } else if (document.body.scrollHeight > document.body.offsetHeight){ // all but Explorer Mac
        xScroll = document.body.scrollWidth;
        yScroll = document.body.scrollHeight;
    } else { // Explorer Mac...would also work in Explorer 6 Strict, Mozilla and Safari
        xScroll = document.body.offsetWidth;
        yScroll = document.body.offsetHeight;
    }

    var windowWidth, windowHeight;
    if (self.innerHeight) {    // all except Explorer
        windowWidth = self.innerWidth;
        windowHeight = self.innerHeight;
    } else if (document.documentElement && document.documentElement.clientHeight) { // Explorer 6 Strict Mode
        windowWidth = document.documentElement.clientWidth;
        windowHeight = document.documentElement.clientHeight;
    } else if (document.body) { // other Explorers
        windowWidth = document.body.clientWidth;
        windowHeight = document.body.clientHeight;
    }

    // for small pages with total height less then height of the viewport
    if(yScroll < windowHeight){
        pageHeight = windowHeight;
    } else {
        pageHeight = yScroll;
    }

    // for small pages with total width less then width of the viewport
    if(xScroll < windowWidth){
        pageWidth = windowWidth;
    } else {
        pageWidth = xScroll;
    }

    arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight)
    return arrayPageSize;
}