var activeIdx = -1;

function activate(idx, bgColor) {
	if (null == bgColor) bgColor = "#F7F7F7";
	if (-1 != activeIdx) {
		deactivate(activeIdx);	
	}
	
	if (idx == activeIdx) {
		deactivate(idx);
		activeIdx = -1;
		return;
	}
	activeIdx = idx;
	var question = document.getElementById("question_" + idx);
	question.style.backgroundColor = bgColor;

	// changing selected question to bold style...
	var tbl = getChild( getChild(question, "TD"), "TABLE");
	for (i=0; i<tbl.cells.length; i++) {
		tbl.cells[i].style.fontWeight = "bold";
	}

	var answer = document.getElementById("answer_" + idx);
	answer.style.display = "";
	try {
		var answerLine = document.getElementById("answer_" + idx + "_line");
		answerLine.style.display = "";
	} catch(err) { }
}

function deactivate(idx) {
	var question = document.getElementById("question_" + idx);
	question.style.backgroundColor = "";
	var answer = document.getElementById("answer_" + idx);
	answer.style.display = "none";
	
	// changing selected question to normal style...
	var tbl = getChild( getChild(question, "TD"), "TABLE");
	for (i=0; i<tbl.cells.length; i++) {
		tbl.cells[i].style.fontWeight = "normal";
	}
	
	try {
		var answerLine = document.getElementById("answer_" + idx + "_line");
		answerLine.style.display = "none";
	} catch(err) { }
}

function getChild(el, childName) {
	for (i=0; i<el.childNodes.length; i++){
		if (el.childNodes[i].nodeName==childName) {
			return el.childNodes[i];
		}
	}	
}

function activate_cs(idx) {
	if (-1 != activeIdx) {
		deactivate_cs(activeIdx);	
	}
	
	if (idx == activeIdx) {
		deactivate_cs(idx);
		activeIdx = -1;
		return;
	}
	activeIdx = idx;
	var question = document.getElementById("question_" + idx);
	question.style.display = "none";
	var question_on = document.getElementById("question_on_" + idx);	
	question_on.style.display = "";
	var answer = document.getElementById("answer_" + idx);
	answer.style.display = "";
	var answerLine = document.getElementById("answer_" + idx + "_line");
	answerLine.style.display = "";
}

function deactivate_cs(idx) {
	var question = document.getElementById("question_" + idx);
	question.style.display = "";
	var question_on = document.getElementById("question_on_" + idx);	
	question_on.style.display = "none";
	var answer = document.getElementById("answer_" + idx);
	answer.style.display = "none";
	var answerLine = document.getElementById("answer_" + idx + "_line");
	answerLine.style.display = "none";
}