function showRecentMsgClick(senderId, senderName, msgId, userId) {
var o = event.srcElement;
while ("IMG" != o.tagName){
o = o.parentElement;
}
var img = o;
while ("TR" != o.tagName){
o = o.parentElement;
}
o = o.nextSibling;
if ('none' == o.style.display){
img.src = document.all.actForm.unfoldImg.value;
showHistoryMsg(senderId, senderName, msgId, userId, o);
o.style.display = 'block';
} else {
img.src = document.all.actForm.initImg.value;
o.style.display = 'none';
}
}
obj.previousSibling是取前一个元素
obj.nextSibling是取后一个元素