function HideAllContent() {
	var nr1 = document.getElementById('1');
	var nr2 = document.getElementById('2');
	var nr3 = document.getElementById('3');
	var nr4 = document.getElementById('4');
	
	var txt1 = document.getElementById('tekst_1');
	var txt2 = document.getElementById('tekst_2');
	var txt3 = document.getElementById('tekst_3');
	var txt4 = document.getElementById('tekst_4');
	
	var st1 = document.getElementById('1_link');
	var st2 = document.getElementById('2_link');
	var st3 = document.getElementById('3_link');
	var st4 = document.getElementById('4_link');
	
	nr1.style.visibility = "hidden";
	nr2.style.visibility = "hidden";
	nr3.style.visibility = "hidden";
	nr4.style.visibility = "hidden";
	
	if (txt1 == '') {
		txt1.style.visibility = "hidden";
		txt1.style.display = "none";
	}
	if (txt2 == '') {
		txt2.style.visibility = "hidden";
		txt2.style.display = "none";
	}
	if (txt3 == '') {
		txt3.style.visibility = "hidden";
		txt3.style.display = "none";
	}
	if (txt4 == '') {
		txt4.style.visibility = "hidden";
		txt4.style.display = "none";
	}

	st1.className = 'button_middenvenster';
	st2.className = 'button_middenvenster';
	st3.className = 'button_middenvenster';
	st4.className = 'button_middenvenster';
	
	nr1.style.display = "none";
	nr2.style.display = "none";
	nr3.style.display = "none";
	nr4.style.display = "none";
}
function Show1() {
	var obj= document.getElementById('1');
	var txt= document.getElementById('tekst_1');
	var link = document.getElementById('1_link');
	if(txt) {
		txt.style.visibility = "visible";
		txt.style.display = "block";
	}
	obj.style.visibility = "visible";
	obj.style.display = "block";
	link.className = 'button_middenvenster_a';
}
function Show2() {
	var obj= document.getElementById('2');
	var txt= document.getElementById('tekst_2');
	var link = document.getElementById('2_link');
	if(txt) {
		txt.style.visibility = "visible";
		txt.style.display = "block";
	}
	obj.style.visibility = "visible";
	obj.style.display = "block";
	link.className = 'button_middenvenster_a';
}
function Show3() {
	var obj= document.getElementById('3');
	var txt= document.getElementById('tekst_3');
	var link = document.getElementById('3_link');
	if(txt) {
		txt.style.visibility = "visible";
		txt.style.display = "block";
	}
	obj.style.visibility = "visible";
	obj.style.display = "block";
	link.className = 'button_middenvenster_a';
}
function Show4() {
	var obj= document.getElementById('4');
	var txt= document.getElementById('tekst_4');
	var link = document.getElementById('4_link');
	if(txt) {
		txt.style.visibility = "visible";
		txt.style.display = "block";
	}
	obj.style.visibility = "visible";
	obj.style.display = "block";
	link.className = 'button_middenvenster_a';
}