great productivity booster!

打开的网页都是pc端的

Side View is a pre-release (major release 0.4. ...) and is presented as part of the pre-release Test Pilot project. This misrepresents Side View as a completed product when it is not.

have not got started yet

This is a great Addon. So far so good.
Feedback
In any YouTube video, I can't find horizontal scroll bar. Also there are two huge horizontal black bar. (What I'm trying to say is that the Addon is unable to adjust according to the video's aspect ratio.
Again, great Addon.

very useful extension :)

Love this feature, thanks! Am so glad I discovered it. A bit concerned that Firefox Test Pilot seems to have ended (before I even discovered it). Hope that this excellent add-on does not disappear.

Great tool for developers! You can see the desktop and mobile versions of a page in one window.

An excellent tool. So useful across so many situations. One of the best is the ability to have my password manager available full time in the sidebar while updating logins. Or simply, anytime I want to keep an important site open and visible while doing other things. Should be a standard feature.

Great tool but still need enhancement. Hope that a refresh, back and next page item will be added to the right-click context menu when click on side view.

It is great to see this option available after Firefox got rid of their sidebar option when they released a previous update. No idea why they got rid of the old sidebar as it was better than this sideview. With sideview You have to remember to right click the bookmark and then press open in sidebar. With the older Firefox sidebar you just pressed the bookmark and it would open in the sidebar. Its just a small thing really but when you are used to that workflow it takes a while to get into this new way of working.

All sideview needs is a checkbox option to state that when this bookmark is pressed it will always open the bookmark in the sidebar.