var agent=navigator.userAgent.toLowerCase();
var version = parseInt(navigator.appVersion);

var is_ie     = ((agent.indexOf("msie") != -1) && (agent.indexOf("opera") == -1));
var is_ie3    = (is_ie && (version < 4));
var is_ie4    = (is_ie && (version == 4) && (agent.indexOf("msie 4")!=-1) );
var is_ie4up  = (is_ie && (version >= 4));
var is_ie5    = (is_ie && (version == 4) && (agent.indexOf("msie 5.0")!=-1) );
var is_ie5_5  = (is_ie && (version == 4) && (agent.indexOf("msie 5.5") !=-1));
var is_ie5up  = (is_ie && !is_ie3 && !is_ie4);
var is_ie5_5up =(is_ie && !is_ie3 && !is_ie4 && !is_ie5);
var is_ie6    = (is_ie && (version == 4) && (agent.indexOf("msie 6.")!=-1) );
var is_ie6up  = (is_ie && !is_ie3 && !is_ie4 && !is_ie5 && !is_ie5_5);

function toggleLeesverder(nummer, open)
{
	var leesverderknop = document.getElementById('leesverder'+nummer+'knop');
	var leesverdertekst = document.getElementById('leesverder'+nummer);
	var blok = document.getElementById('blok'+nummer);
	
	blok.style.height= open ? 'auto' : '185px';
	if(is_ie5_5up)
	{
		leesverdertekst.style.filter='progid:DXImageTransform.Microsoft.Fade(duration=1)';
		leesverdertekst.filters[0].Apply();
	}
	leesverderknop.style.display= open ? 'none' : '';
	leesverdertekst.style.display= open ? 'block' : '';
	if(is_ie5_5up)
	{
		leesverdertekst.filters[0].Play();	
	}
	
}