function zobrazSkryj(idecko)
{
  blok = 'b_' + idecko;
	odr = 'p_' + idecko;
	el=document.getElementById(blok).style;
	el.display=(el.display == 'block')?'none':'block';
	//window.alert(el.display);
	if (el.display == 'block') document[odr].src='./obr/minus.gif';
	if (el.display == 'none') document[odr].src='./obr/plus.gif';
}