function init_menu() {
	if (!document.getElementsByTagName) { return; }
	var gallery_controls = document.getElementsByTagName("a");

    // buttons
    var sub_but_6 = document.getElementById('sub_newwork');
	var sub_but_1 = document.getElementById('sub_exhibitions');
    var sub_but_2 = document.getElementById('sub_sitespecific');
	var sub_but_3 = document.getElementById('sub_cutouts');
	var sub_but_4 = document.getElementById('sub_timebased');
	var sub_but_5 = document.getElementById('sub_photographs');
    // sub menus
    var sub_menu_6 = document.getElementById('newwork');
	var sub_menu_1 = document.getElementById('exhibitions');
    var sub_menu_2 = document.getElementById('sitespecific');
	var sub_menu_3 = document.getElementById('cutouts');
	var sub_menu_4 = document.getElementById('timebased');
	var sub_menu_5 = document.getElementById('photographs');
    
	sub_but_6.onclick=function() {
        if(sub_menu_6.style.display=='block') {
            sub_menu_6.style.display='none';
        } else {
            sub_menu_6.style.display='block';
        }
    }
	sub_but_1.onclick=function() {
        if(sub_menu_1.style.display=='block') {
            sub_menu_1.style.display='none';
        } else {
            sub_menu_1.style.display='block';
        }
    }
    sub_but_2.onclick=function() {
        if(sub_menu_2.style.display=='block') {
            sub_menu_2.style.display='none';
        } else {
            sub_menu_2.style.display='block';
        }
    }
    sub_but_3.onclick=function() {
        if(sub_menu_3.style.display=='block') {
            sub_menu_3.style.display='none';
        } else {
            sub_menu_3.style.display='block';
        }
    }
	    sub_but_4.onclick=function() {
        if(sub_menu_4.style.display=='block') {
            sub_menu_4.style.display='none';
        } else {
            sub_menu_4.style.display='block';
        }
    }
	sub_but_5.onclick=function() {
        if(sub_menu_5.style.display=='block') {
            sub_menu_5.style.display='none';
        } else {
            sub_menu_5.style.display='block';
        }
    }
	
}