Yettwasezmel 1 ɣef 5 n yetran

sɛur Shudushi di Aug. 28, 2017 · aseɣwen yezgan

It WAS one of my favorite Add-on's, but v1.7.1 doesn't work anymore with Firefox v55+.

You can find a similar, but still working Add-on here:
https://addons.mozilla.org/en-US/firefox/addon/browsizer

It works for me on 55.0.3 (32bit) together with Add-on "New Add-on Bar" here:
https://addons.mozilla.org/de/firefox/addon/new-add-on-bar

Hope it does it also 4U!