gecko/toolkit/themes/pinstripe/global/resizer.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

resizer[dir="top"],
resizer[dir="bottom"] {
  cursor: ns-resize;
}

resizer[dir="left"],
resizer[dir="right"] {
  cursor: ew-resize;
}

resizer[dir="topleft"] {
  cursor: nw-resize;
}

resizer[dir="bottomright"],
resizer[dir="bottomend"][chromedir="ltr"] {
  cursor: se-resize;
}

resizer[dir="topright"] {
  cursor: ne-resize;
}

resizer[dir="bottomleft"],
resizer[dir="bottomend"][chromedir="rtl"] {
  cursor: sw-resize;
}