function show_hide_layer( whichLayer ) {
	if ( document.getElementById ) {
		// this is the way the standards work
		var element = document.getElementById( whichLayer );
	}
	else if ( document.all ) {
		// this is the way old msie versions work
		var element = document.all[ whichLayer ];
	}
	else if ( document.layers ) {
		// this is the way nn4 works
		var element = document.layers[ whichLayer ];
	}
	// zmiana widoczności elementu jeśli istnieje
	// && element.style != null
	if ( element != null ) {
		//alert( 'whichLayer=' + whichLayer + ' => element.style.display=' + element.style.display );
		element.style.display = element.style.display ? "" : "block";
	}
}

function show_layer( whichLayer ) {
	if ( document.getElementById ) {
		// this is the way the standards work
		var element = document.getElementById( whichLayer );
	}
	else if ( document.all ) {
		// this is the way old msie versions work
		var element = document.all[ whichLayer ];
	}
	else if ( document.layers ) {
		// this is the way nn4 works
		var element = document.layers[ whichLayer ];
	}
	// zmiana widoczności elementu jeśli istnieje
	// && element.style != null
	if ( element != null ) {
		element.style.display = "block";
	}
}

function hide_layer( whichLayer ) {
	if ( document.getElementById ) {
		// this is the way the standards work
		var element = document.getElementById( whichLayer );
	}
	else if ( document.all ) {
		// this is the way old msie versions work
		var element = document.all[ whichLayer ];
	}
	else if ( document.layers ) {
		// this is the way nn4 works
		var element = document.layers[ whichLayer ];
	}
	// zmiana widoczności elementu jeśli istnieje
	// && element.style != null
	if ( element != null ) {
		element.style.display = "";
	}
}