function changeStyleSample()
{
document.getElementById("mouseoverdiv").style.visibility="visible";
}
function changeStyleBackSample()
{
document.getElementById("mouseoverdiv").style.visibility="hidden";
}
function changeStyleAbout()
{
document.getElementById("mouseoverdiv2").style.visibility="visible";
}
function changeStyleBackAbout()
{
document.getElementById("mouseoverdiv2").style.visibility="hidden";
}

function hideAbout()
{
document.getElementById("about_container").style.visibility="hidden";
}
function hideSamples()
{
document.getElementById("samples_container").style.visibility="hidden";
}