function toggle_image(div) {
        var d = div;
        if (document.getElementById(d).style.display == 'block') {
      	  document.getElementById(d).style.display = 'none';
				}
      	else {
      	  document.getElementById(d).style.display = 'block';
				}
      }
      // pop-up sign-up and register forms 
     
      function toggle(div_id) {
      	var el = document.getElementById(div_id);
      	if ( el.style.display == 'none' ) {	
				  el.style.display = 'block';
				}
      	else {
				  el.style.display = 'none';
					$.validationEngine.closePrompt(".formError",true);
				}
      }
      
      function blanket_size(popUpDivVar, winSize) {
      	if (typeof window.innerWidth != 'undefined') {
      		viewportheight = window.innerHeight;
      	} else {
      		viewportheight = document.documentElement.clientHeight;
      	}
      	if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
      		blanket_height = viewportheight;
      	} else {
      		if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
      			blanket_height = document.body.parentNode.clientHeight;
      		} else {
      			blanket_height = document.body.parentNode.scrollHeight;
      		}
      	}
      	var blanket = document.getElementById('blanket');
      	blanket.style.height = blanket_height + 'px';
      	var popUpDiv = document.getElementById(popUpDivVar);
      	popUpDiv_height=blanket_height/2-winSize;//400 is half popup's height
      	popUpDiv.style.top = 60 + 'px';
      }
      
      function window_pos(popUpDivVar) {
      	if (typeof window.innerWidth != 'undefined')
      		viewportwidth = window.innerHeight;
      	else
      		viewportwidth = document.documentElement.clientHeight;

      	if ((viewportwidth > document.body.parentNode.scrollWidth) && (viewportwidth > document.body.parentNode.clientWidth)) {
      		window_width = viewportwidth;
      	} 
				else 
				{
      		if (document.body.parentNode.clientWidth > document.body.parentNode.scrollWidth)
      			window_width = document.body.parentNode.clientWidth;
      		else 
      			window_width = document.body.parentNode.scrollWidth;
      	}
      	var popUpDiv = document.getElementById(popUpDivVar);
				if (popUpDiv.id == 'register')
      	  window_width=window_width/2-480;//300 is half popup's width
					
				if (popUpDiv.id == 'sign-in')
      	  window_width=window_width/2-250;//150 is half popup's width
					
				if (popUpDiv.id == 'facebook')
      	  window_width=window_width/2-150;//150 is half popup's width		
								
      	popUpDiv.style.left = window_width + 'px';
      }
      
      function popup(windowname, winSize) {
      	blanket_size(windowname, winSize);
      	window_pos(windowname);
      	toggle('blanket');
      	toggle(windowname);
				//alert(windowname);
      }
			
			function register() {
			  document.getElementById('sign-in').style.display = 'none';
				document.getElementById('blanket').style.display = 'none';
			  popup('register', 700);
			}