[jule]

Вот так как-то:

function hidetxt(){
	var tags = document.body.getElementsByTagName("*"),getStyle;
	for(var i = 0; i < tags.length; i++){
		if (window.getComputedStyle)
			getStyle = getComputedStyle(tags[i]);
		else getStyle = tags[i].currentStyle;
		if(tags[i].id){
			if(getStyle.display == "block")
				tags[i].style.display = "none";
	
			else tags[i].style.display = "block";
		}
	}
}