function showTab (tabID){
//verberg tabA t/m tabD
//maak breedte tabA t/m tabD 325
x = document.getElementById("tabA");
x.style.visibility = 'hidden';
x.style.width = '325px';
x.style.padding = '5px';
x = document.getElementById("tabB");
x.style.visibility = 'hidden';
x.style.width = '325px';
x.style.padding = '5px';
x = document.getElementById("tabC");
x.style.visibility = 'hidden';
x.style.width = '325px';
x.style.padding = '5px';
x = document.getElementById("tabD");
x.style.visibility = 'hidden';
x.style.width = '325px';
x.style.padding = '5px';

//laat alleen tabID zien
x = document.getElementById(tabID);
x.style.visibility = 'visible';

//toon de juiste schtergrondfoto
x = document.getElementById("achtergrondfoto");
x.src = achtergrondfoto[tabID];
document.getElementById('tabpijl').style.visibility = 'hidden'
}

function schuifWeg(id1, millisec) {
	//speed for each frame
	var speed = Math.round(millisec / 100);
	var timer = 0;
  x = document.getElementById(id1);
		for(i = 325; i >= 0; i = i-2) {
			setTimeout("x.style.width = '" + i + "px'",(timer * speed));
			timer++;
		}
		setTimeout("x.style.width = '" + 0 + "px'",(timer * speed));
		setTimeout("x.style.padding = '" + 0 + "px'",(timer * speed));
		activeTab = id1;
		setTimeout("document.getElementById('tabpijl').style.visibility = 'visible'",(timer * speed));
}

function schuifOp(id2, millisec) {
	//speed for each frame
	var speed = Math.round(millisec / 100);
	var timer = 0;
  y = document.getElementById(id2);
		setTimeout("y.style.padding = '" + 5 + "px'",(timer * speed));
		for(i = 0; i <= 325; i = i+2) {
			setTimeout("y.style.width = '" + i + "px'",(timer * speed));
			timer++;
		}
		document.getElementById('tabpijl').style.visibility = 'hidden';
}

function rollDown(id2) {
  y = document.getElementById(id2);
	if(y.style.visibility == "visible"){
	y.style.height = "0px";
	y.style.visibility = "hidden";
	} else {
	y.style.height = "";
	y.style.visibility = "visible";
	}
}

function showFoto(fotoSRC, fotoALT){
x = document.getElementById("achtergrondfoto");
x.src = fotoSRC;
x.alt = fotoALT;
}