//function to display or hide a given element

function showHideItems(myItem, myButton)
{

	//this is the ID of the hidden item
	var myItem = document.getElementById(myItem);


	//this is the ID of the plus/minus button image
	var myButton = document.getElementById(myButton);

	if (myItem.style.display != "none") 
	{
		//items are currently displayed, so hide them
		myItem.style.display = "none";
		swapImage(myButton,"plus");
	}
	else 
	{

		//items are currently hidden, so display them
		myItem.style.display = "block";
		swapImage(myButton,"minus");
	}
}

//function to swap an image based on its current state
function swapImage(myImage, state) 
{
	if (state == "minus") 
	{
		myImage.src = "images/minus.gif";
	}

	else 
	{
		myImage.src = "images/plus.gif";
	}
}