function bindCheckbox(el)
{
	_element = _(el);
	if( _element )
	{
		hideEl('_delAll' );
		doCheckboxes( _element );
		_element.onclick = function(){
			doCheckboxes(this)
		}
	}
}

function countCheckedCheckboxes( class_name )
{
			checkboxes =  document.getElementsByClassName( class_name );
			counter = 0;
			for( i = 0, j = checkboxes.length; i < j; i++ )
			{
				if( checkboxes[i].checked )
				{
					counter++;
				}
			}
			return counter;
}
	
function doCheckboxes(_element )
{
			checkboxes =  document.getElementsByClassName( '_check' );
			if( _element.checked )
			{
				showEl( '_delAll' );
			}
			else
			{
				hideEl( '_delAll' );
			}		
			for( i = 0, j = checkboxes.length; i < j; i++ )
			{
				box = checkboxes[i];
				
				box.onclick = function()
				{
					if( countCheckedCheckboxes('_check') > 0 )
					{
						showEl('_delAll');
					}
					else
					{
						hideEl('_delAll');
					}
				}	
				
				if( _element.checked )
				{
					box.checked = 'checked';
				}
				else
				{
					box.checked = false;
				}
			}
}

function hideEl(el)
{
	c = _(el);
	if( c )
	{
		c.style.display = 'none';
	}
}

function showEl(el)
{
	c = _(el);
	if( c )
	{
		c.style.display = 'inline';
	}
}

function _(El)
{
	return document.getElementById(El);
}


window.onload = function() 
{
	bindCheckbox('_checkAll');
}