I enjoy this addon overall, howerver, there are downsides:
- it's not working in Reader View mode
- as opposed to FireGestures it disables right click context menu and makes it only available upon double click ("double-click right button to pop-up context menu")
- going up one level in domain names (e.g. https://addons.mozilla.org/en-US/firefox/addon/smartup/ -> https://addons.mozilla.org/en-US/firefox/addon/ ) is not available. It might be fixable w/ custom scripts but I couldn't find documentation as smartup.zimoapps.com is down
- no documentation for custom scripts