Don’t believe you can if you stick it in a partial. Partials are intended to be a component that you can use multiple times that updates on every page if you change something within. If you’re going to be changing the backgrounds on every page, it’s all going to get updated to the same image.
Yes, I use partials with drag and drop both inside and outside of the partial to change text, and buttons, but I suppose if the overlay background is part of the stack, I won’t be able to. Just wanted to make sure.
Ah yes partials are fine within the stack it’s just making the entire section a partial ain’t going to work if you wanna change the background. Perhaps Andrew can prove me wrong but I don’t think it’s possible.
I think the question actually refers to the opposite situation - i.e. is it possible to set up a stack as a partial but then have an “un-pinned” background that can be changed on a per stack basis.
The answer to this question is unfortunately no. Settings cannot be unpinned in Partials and given that the background (and other child stack images) are specified in the settings panel there is no way to change them once made into a partial.
The best solution though does come back to the answers mentioned above. Just use a ProStyles layout master as a partial for the Section layout and then apply this to whichever individual stacks you like with their different backgrounds.
You can of course use Easy & Total CMS images to change backgrounds on a per stack basis even in a partial but I think this is probably beyond the scope of the original question.