// This function makes the menu and sub-menu change dynamically when
// used with the onMouseOver event handler.
//
function changeMenus( menuID, subMenuID )
{
	// First check if the browser is compatible with the objects
	// in the DOM.
	//
	if( document.getElementById )
	{
		// Set all of the menu choices to the non-highlight colour.
		//
		document.getElementById( 'menuHome' ).style.color = '#99CC99';
		document.getElementById( 'menuServices' ).style.color = '#99CC99';
		document.getElementById( 'menuHelpCentre' ).style.color = '#99CC99';
		document.getElementById( 'menuPortfolio' ).style.color = '#99CC99';
		document.getElementById( 'menuPromotions' ).style.color = '#99CC99';
		document.getElementById( 'menuContact' ).style.color = '#99CC99';
		
		// Highlight the appropriate menu option
		//
		document.getElementById( menuID ).style.color = '#ffffff';
		
		// Hide any sub-menu that may be showing so the new menu
		// looks clean.
		//
		document.getElementById( 'subMenuServices' ).style.visibility = 'hidden';
		document.getElementById( 'subMenuHelpCentre' ).style.visibility = 'hidden';
		document.getElementById( 'subMenuPortfolio' ).style.visibility = 'hidden';
		document.getElementById( 'subMenuDefault' ).style.visibility = 'hidden';
		
		// Show the desired subMenu.
		//
		document.getElementById( subMenuID ).style.visibility = 'visible';
	}
}