I already had to guess when I read the description:
"Adds a "open background image in new tab" menu item." Where on earth is this menu item located?!! On the new tab page I assume!

Then, I go to this new tab page, I click on the top right "Customize your new tab page" button that I assume is this menu (for the menu item mentioned) and it does not show up!

Then, I read the 1 star comment made by the developer and I read:
"Hello, I currently have it in firefox 59 and it is working very well, if you are using any advertising blocker, disable it"
And I say to myself: disable my ad blocker addon just to have a picture on my new tab page??!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! What on earth this developer has been drinking or smoking lately?!!!

Advice: always be very clear, extremely clear on the way you describe your product. I still have no clue what you mean by "menu item" without identifying where this menu item is located on the browser! It could mean many things!!