/**
 * show/hide cool global overlay
 *
 * Created on 11.09.2008
 * Project: asurvey
 *
 * '$Id: cool.js,v 1.5 2009/06/18 08:57:17 abaethe Exp $'
 *
 */


/**
 * display/hide grey overlay div
 * NOTE: normally all selects are disabled (because of bad interactions with some browsers), 
 *       except "toggleGlobalOverlay('noselectchange')" is called
 */
function toggleGlobalOverlay(noselectchange)    
{
  var go = document.getElementById('grey_overlay');
  var fr = document.getElementById('body');
  var go_v = go.style.visibility;

  // have to set height dynamically because css-100% would refer to visible browser-window only, not whole html-height
  go.style.height = (fr.scrollHeight > fr.offsetHeight ? fr.scrollHeight : fr.offsetHeight) + "px";   // (offset|scroll)Height have only a getter
  
  var body_selects = document.getElementsByTagName("select");

  if( !go_v || (go_v == 'hidden') )
  {
    document.getElementById('grey_overlay').style.visibility = 'visible';
    if( noselectchange != 'noselectchange' )
      for( i = 0; i < body_selects.length; i++ )
        body_selects[i].style.visibility = "hidden";
  }
  else
  {
    document.getElementById('grey_overlay').style.visibility = 'hidden';
    if( noselectchange != 'noselectchange' )
      for( i = 0; i < body_selects.length; i++ )
        body_selects[i].style.visibility = "visible";
  }
}