function preload(imgObj,imgSrc) 
{
   eval(imgObj+' = new Image()')
   eval(imgObj+'.src = "'+imgSrc+'"')
}

preload('foreign_policy_on','/images/foreign_policy_on.gif');
preload('foreign_policy_off','/images/foreign_policy_off.gif');	

preload('int_dev_on','/images/int_dev_on.gif');
preload('int_dev_off','/images/int_dev_off.gif');	

preload('defence_on','/images/defence_on.gif');
preload('defence_off','/images/defence_off.gif');	

preload('trade_policy_on','/images/trade_policy_on.gif');
preload('trade_policy_off','/images/trade_policy_off.gif');

function img_toggle( imgName, mode ) 
{
   if( document.images ) 
   {
      document[ imgName ].src = eval( imgName + "_" + mode + ".src" );
   }
}