function zobrazSkryj(obr,zmena){
              if (zmena == true) {
                var idecko = 'preview';
                var idecko2 = 'preview_bg';
                var idecko3 = 'preview_close';

               
                ek=document.getElementById(idecko2).style;
                el=document.getElementById(idecko).style;
                
               
                ek.display=(ek.display == 'block')?'none':'block';
                el.display=(el.display == 'block')?'none':'block';
              }

              var next_script = "'"+obr+"',false";
              var prev_script = "'"+obr+"',false";
              var next_img = '<img src="img/next_pic_arrow.gif" border=0 />';
              var prev_img = '<img src="img/prev_pic_arrow.gif" border=0 />';
              var close_img = '<img src="images/close.gif" border=0 />';              
              var close_script = "'"+obr+"',true";
              var width = screen.availWidth;
              var height = screen.availHeight;
              var style = 'style="float:left; background-color:#777; norepeat left top; border:0px;"'
              var lista = '<p style="text-align:right; display:block; margin:2px 0px 0px 20px;"><a href="#" onClick="zobrazSkryj('+close_script+'); return false;">'+close_img+'</a></p>';
              document.getElementById(idecko).innerHTML='<div '+style+'/><a href="#" style="border:0px;" onClick="zobrazSkryj('+close_script+'); return false;"><img style="border:0px;" src="'+obr+'" /></a></div>';
              document.getElementById(idecko2).style.width=width;
              document.getElementById(idecko2).style.height=(height*2);
              document.getElementById(idecko).style.left=((width/2)-420);
              }