Uhm, I guess I'll just copy the patch contents here since my link to pastebin expired long ago.
Just add a call to updateStrutSize() at the end of Harbour::setStateHidden(StateAction sa), and then update the if condition in Harbour::updateStrutSize(void) from:
if (! Config::instance()->isHarbourMaximizeOver()) {
to:
if (! (Config::instance()->isHarbourMaximizeOver() || _hidden)) {
PS: I totally don't understand how to specify code fragments on this text-area. Hence the ugly patch explanation rather than pasting the contents here. :/