panel sit_button
{
flags=visible;
bmap=sitbutton;
on_click=turn_sleep;
}

panel sleep_button
{
bmap=sleepbutton;
on_click=turn_sit;
}

function turn_sleep
{
sit_button.visible=off;
sleep_button.visible=on;
}

function turn_sit
{
sit_button.visible=on;
sleep_button.visible=off;
}