Exactly the thing to get to improve on Firefox Quantum's horrible default image viewer that not only adds back in features that previous Firefox versions had, but additional features as well. All of this with a good looking interface to boot.

Could you provide a feature to rotate image?

Too fast zooming for macOS Trackpad...

Firefox should include zoom with mouse by default.

Is it possible to add buttons to rotate images on the side menu? Kinda miss those honestly.

This should come with firefox out of the box.

Very useful. You need to disable the right-click zoom/fit function, because it's disturbing that the image gets resized while trying to save it with right-click and "Save as...".

Also, would be good if you implement some visual numbering showing the percentage of zooming.

Lastly, a rotate image (by 15 degrees) and a mirror function will be helpful as well. So many times I wanted to see some image mirrored left to right or upside-down, without the need to import the image to an external image editor.

exactly what I need, thank you!

Good and simple to use.

Exactly what I need, no more no less!
Only one suggestion:
Do not hide the scroll bar or make it 50% transparent so we know where is the edge.

Excellent replacement for non-WE extensions. Actually an improvement!
I second suggestion to add image rotate.
Also, zoom to fit window would be nice.

I was pleasantly surprised with this addon. I really like the features, escpesialy the scroll zoom feature. Great job Mr Lankow.

Very simple but useful tool.
Add rotate image and then is perfect.
Thanks.