var prev_el;
var prev_active;

function udalost_menu(e){
if (document.all) var t = window.event.srcElement.id
else if (document.getElementById) var t = e.target.id;

  if ((t == 'm1') || (t == 'm2') || (t == 'm3') || (t == 'm4')){
  index = t.substr(1,1);
  index = 'submenu'+index;
    zobraz(index,t)
  }else {
    skryj_vse(prev_active,prev_el);
  } 
}

function zobraz(f,y){

    document.getElementById(prev_el).style.backgroundColor='#93b6e0';
    document.getElementById(prev_el).style.color='#2a4a86';
		
		
    el=document.getElementById(f).style; 
    if (el.display == 'block')  {
		  skryj_vse(f,y);
		
    }
    else{
    el.display = 'block';
    document.getElementById(prev_active).style.display='none';
    document.getElementById(y).style.backgroundColor='#000000';
    document.getElementById(y).style.color='#ffffff';		
    prev_el = y;
    prev_active = f;
    }
}

function navigace(f,x){
id = 'submenu'+x;
location=f;
document.getElementById(id).style.display='none'; 
return false;
}

function skryj_vse(x,y){
  document.getElementById(x).style.display='none';
  document.getElementById(y).style.backgroundColor='#93b6e0';
  document.getElementById(y).style.color='#2a4a86';
  prev_active='a';
  prev_el='m1';
}