var pre = 'galerie';

function toggleButton(obj) {

	document.getElementById(pre + 'Img').setAttribute('src',
			'/gfx/start_button_' + pre + '.png');
	document.getElementById(pre + 'Img').src = '/gfx/start_button_' + pre
			+ '.png';

	document.getElementById(obj.id + 'Img').setAttribute('src',
			'/gfx/start_button_' + obj.id + '_active.png');
	document.getElementById(obj.id + 'Img').src = '/gfx/start_button_' + obj.id
			+ '_active.png';
	pre = obj.id;
}