function get_inleiding( f , gid )
    {

        var obj = new ajaxObject( f , 'body' , '../system/ajax/get_inleiding.php?id=' + gid );
        obj.update();        
        
    }

    function converse_inleiding_to_geheel( gid )
    {
        document.getElementById('Gedicht_Inleiding').style.display = 'none';
        document.getElementById('Gedicht_Geheel_Invisible').style.display = 'block';
        
        var obj = new ajaxObject( document.forms[0] , 'Gedicht_Header' , 'system/ajax/add_click_lees_verder.php?id=' + gid );
        obj.update();          
        
    }

    function converse_geheel_to_inleiding( )
    {
        document.getElementById('Gedicht_Inleiding').style.display = 'block';
        document.getElementById('Gedicht_Geheel_Invisible').style.display = 'none';
    }    

	function show_geheel( f , gid )
	{
		var obj = new ajaxObject( f , 'main_txt' , 'system/ajax/get_gedicht_tekst.php?id=' + gid );
		obj.update();
	}

	function show_inleiding( f , gid )
	{      
		var obj = new ajaxObject( f , 'Gedicht_Header' , 'system/ajax/get_gedicht_header.php?id=' + gid );
		obj.update();

        var obj = new ajaxObject( f , 'Gedicht_Inleiding' , 'system/ajax/get_gedicht_tekst_inleiding.php?id=' + gid );
        obj.update();

        var obj = new ajaxObject( f , 'Gedicht_Geheel_Invisible' , 'system/ajax/get_gedicht_tekst_invisible.php?id=' + gid );
        obj.update();

        //set inleiding to visible
        converse_geheel_to_inleiding( );
        
	}
	
	
	function logout(url)
	{
		if ( confirm( 'Weet je zeker dat je wilt uitloggen?' ) )
		{
			document.location = url;
		}
	}
	

	function checkChars( sText , ValidChars )
	{

		var IsNumber=true;
		var Char;

		for (i = 0; i < sText.length && IsNumber == true; i++) 
		{ 
			Char = sText.charAt(i); 
			if (ValidChars.indexOf(Char) == -1) 
			{
				//alert( 'Teken: ' + Char + ' (' + sText + '-' + ValidChars + ')' );
				IsNumber = false;
			}
		}
		return IsNumber;
   
	}