Thank you. It kind of makes sense, but it also tells me that Stocky is not correctly designed in a way. I don’t think the code should need to be tweaked. Here is why I say that:
WordPress is designed so that normally your featured image displays as a thumbnail for your posts. Then if you want to add images to the posts you put them within the body of the post as Add Media. So this is how you normally make the images displayed in the post and the thumbnail/featured image for a post to be different. I know you know this of course, but I am just going through the steps to make a point.
The problem is that the way Stocky is designed is that it a product/download page it moves what would be the normal post box area to and area below where the post box would be and in the normal post box area it is designed so that it can only put in either the featured image or an oEmbed link into that area. It doesn’t actually allow you to add post text or media to the normal post area the way WordPress is designed.
As a result, the only way you can force some media into the normal post area is to host it elsewhere and use an oEmbed link. That is a poor design decision IMHO. If the theme developer wanted to allow the user to use the featured image as part of the post then the theme could have simply been coded so that if there is no media added to the post itself, and no oEmbded links added either, then by default it adds the featured image as the display image for the Download page. But that way it would at least allow you to put your own image into the main area of a product page. But the way it is designed it doesn’t work if someone wants to put their own image into the main display area for a product page.
Sure, you can still Add Media to the main post area when you are creating a product page, but then it displays it down below and you still end up with the Featured Image in the main display area above it. That of course doesn’t work
I understand how your suggestion of the Multiple Post Thumbs plugin could work with a code tweak to the Stocky theme, but that is just putting a bandage on an already bad design decision. And it also isn’t as simple as just putting in the plugin. You would still need to tweak the Stocky code as you said and in my belief the theme should have simply been designed better to accommodate this situation.
In the most simple of examples of when it would be necessary to have the product page image to be a different image as the thumbnail is because you normally would want to put a watermark on the larger version of the image that displays on the product page. But if that same image shows as the thumbnail in searches it makes it more difficult for a buyer to look at the thumbnail if it also contains the watermark. You want a clean thumbnail and a display image that has a watermark.
In my opinion it is obvious the developer did not consider the fact that most people who would be using the theme to sell stock photos would want to watermark their product page images because, if you look at the Stocky demo site, the developer has put large images into the product pages which contain no watermarks. Any potential photo buyer looking for images only for web use then can easily just take the large product display image and use that since it would be big enough for web use in most cases and contains no watermarks. No need for the buyer to buy the image anymore at that point. Since stock photos sales is in fact what the theme is really designed for anyway you would think the developer would have taken this into consideration.
If you look at any stock photo site, every sample image provided on any stock photos is always watermarked, no matter how big or small. I don’t see how the developer would not have taken this issue into consideration when designing.
Just my 2 cents and probably this all doesn’t matter to you. But the way the theme is designed I can’t see buying it because of this issue.