function rollOver(imName,idx,over) {
    if (over) { document.images[imName+idx].src = "images/" + imName + "_not_pressed_active.png" }
         else { document.images[imName+idx].src = "images/" + imName + "_not_pressed.png" }
}

function rollPress(imName,idx,down) {
    if (down) { document.images[imName+idx].src = "images/" + imName + "_pressed.png" }
         else { document.images[imName+idx].src = "images/" + imName + "_not_pressed_active.png" }
}