function divablak_kozepre()
{
	//alert(divablak_hc+'\n'+G_('divablak_'+divablak_hc))
	if(G_('divablak_'+divablak_hc).style.display == 'block')
	{
		var viewportwidth;
		var viewportheight;
		
		if (typeof window.innerWidth != 'undefined')
		{
			//pl. firefox 3.6
			viewportwidth = window.innerWidth;
			viewportheight = window.innerHeight;
			scrollleft = window.pageXOffset;
			scrolltop = window.pageYOffset;
		}
		else if (typeof document.documentElement != 'undefined' && typeof document.documentElement.clientWidth != 'undefined' && document.documentElement.clientWidth != 0)
		{
			//pl. IE6
			viewportwidth = document.documentElement.clientWidth;
			viewportheight = document.documentElement.clientHeight;
			scrollleft = document.documentElement.scrollLeft;
			scrolltop = document.documentElement.scrollTop;
		}
		else
		{
			viewportwidth = document.getElementsByTagName('body')[0].clientWidth;
			viewportheight = document.getElementsByTagName('body')[0].clientHeight;
			scrollleft = document.getElementsByTagName('body')[0].scrollLeft;
			scrolltop = document.getElementsByTagName('body')[0].scrollTop;
		}

		//alert('w:'+G_('divablak').offsetWidth+'\nh:'+G_('divablak').offsetHeight+'\nl:'+G_('divablak').style.left+'\ntop:'+G_('divablak').style.top+'\nw w:'+viewportwidth+'\nw h:'+viewportheight)
		
		var l = (scrollleft + (viewportwidth - G_('divablak_'+divablak_hc).offsetWidth)/2);
		var t = (scrolltop + (viewportheight - G_('divablak_'+divablak_hc).offsetHeight)/2)
		
		l = (l > scrollleft)? l : scrollleft;
		t = (t > scrolltop)? t : scrolltop;
		//alert(scrollleft+'\n'+scrolltop+'\n\n'+viewportwidth+'\n'+viewportheight);
		G_('divablak_'+divablak_hc).style.left = l+'px';
		G_('divablak_'+divablak_hc).style.top = t+'px';
	}
}