function showIFrameDiv(Xwidth,Yheight,url,iframeid) {
	// First, determine how much the visitor has scrolled
	
	var scrolledX, scrolledY; 
	if( self.pageYOffset ) { 
		scrolledX = self.pageXOffset; 
		scrolledY = self.pageYOffset; 
	} else if( document.documentElement && document.documentElement.scrollTop ) { 
		scrolledX = document.documentElement.scrollLeft; 
		scrolledY = document.documentElement.scrollTop; 
	} else if( document.body ) { 
		scrolledX = document.body.scrollLeft; 
		scrolledY = document.body.scrollTop; 
	}
	
	// Next, determine the coordinates of the center of browser's window
	
	var centerX, centerY; 
	if( self.innerHeight ) { 
		centerX = self.innerWidth; 
		centerY = self.innerHeight; 
	} else if( document.documentElement && document.documentElement.clientHeight ) { 
		centerX = document.documentElement.clientWidth; 
		centerY = document.documentElement.clientHeight; 
	} else if( document.body ) { 
		centerX = document.body.clientWidth; 
		centerY = document.body.clientHeight; 
	}
	
	// Xwidth is the width of the div, Yheight is the height of the 
	// div passed as arguments to the function: 
	var leftOffset = scrolledX + (centerX - Xwidth) / 2; 
	var topOffset = scrolledY + (centerY - Yheight) / 2; 
 
	var o=document.getElementById(iframeid); 
	var r=o.style; 
	r.backgroundColor = 'white';
	r.padding = '8px';
	r.borderStyle = 'solid';
	r.borderWidth = '5px';
	r.borderColor = '#AAAAAA';
	r.position='absolute'; 
	r.top = topOffset + 'px'; 
	r.left = leftOffset + 'px'; 


	var objOverlay = document.getElementById("darkoverlay");
	
	var arrayPageSize = getPageSize();
	var arrayPageScroll = getPageScroll();
	// set height of Overlay to take up whole page and show
	objOverlay.style.height = (arrayPageSize[1] + 'px');
	objOverlay.onclick = function () {hideIFrameDiv(iframeid); return false;}
	objOverlay.style.display = 'block';

	r.display = "block";

	if (url != '') {
		o.src = url;
	}
}

function hideIFrameDiv(iframeid)
{
	var objOverlay = document.getElementById('darkoverlay');
	objOverlay.style.display = 'none';
	var o = document.getElementById(iframeid);
	o.style.display = 'none';
}

function validate() {
	var name = document.getElementById("name");
	if (name.value.length==0 ) {
		alert('請輸入您的姓名。');
		name.focus();
		return false;
	}
	var email = document.getElementById("email");
	if (email.value.length==0) {
		alert('請輸入電郵地址。');
		email.focus();
		return false;
	}
	if ( !(email.value.indexOf(".") > 2 && email.value.indexOf("@") > 0) ) {
		alert('請輸入正確的電郵地址。');
		email.focus();
		return false;
	}
	var city = document.getElementById("city");
	if (city.value.length==0 ) {
		alert('請輸入您居住的城市。');
		city.focus();
		return false;
	}
	var comment = document.getElementById("kccomment");
	if (comment.value.length==0 ) {
		alert('請輸入留言。');
		comment.focus();
		return false;
	}

}

function limitText(limitField, limitNum) {
    if (limitField.value.length > limitNum) {
    	alert("留言字數已超過150。");
        limitField.value = limitField.value.substring(0, limitNum);
    }
}

function showBlogDesc(blogID) {
	var e = document.getElementById('blogdesc'+blogID);
	e.style.display = '';
	e.style.background = '#FFFFCC';
	e.style.width = '200px';
}

function hideBlogDesc(blogID) {
	var e = document.getElementById('blogdesc'+blogID);
	e.style.display = 'none';
}