function displayHideUI()
{
     var ui =document.getElementById("bbs");
    ui.style.display="none";
}
function displayShowUI()
{
     var ui =document.getElementById("bbs");
     ui.style.display="";//display为空的话会好使，为block会使后边的空间换行
}
 
 
function visibilityHideUI()
{
     var ui =document.getElementById("bbs");
    ui.style.visibility="hidden";
}
function visibilityShowUI()
{
     var ui =document.getElementById("bbs");
    ui.style.visibility="visible";
}
</script>