Amazing replacement of FireGestures. The options page is a lot more "interactive" than FG's (drawing the gesture instead of entering a sequence of coded directions). Last release (1.0.15) broke something, as Open in New Background Tab is not working at all (maybe it only works on FF Quantum, but the add-on states it works in FF 53 or later, and I'm using FF 56.0.2). Reverted to v1.0.11, which was working fine to me.