Have an addon and it works well now https://github.com/Gl2imm/Apex-Toolbox
Have the intention to add in some of the items for easy use, but the images there are huge and not everyone wants to download addon with 200-300Mb size. Good option is to Optionally download External zip file with images and unpack it, so additional options will pop up to append them.
There is not much info/example about downloads here. Cant figure out at least simple logic for it to work. I looked in Easy PBR code and here How do I Download an External File from URL and Display Progress in a Panel without blocking the UI? but is way too complicated setup.
What I'm trying to do is a simple button on the panel that says "Download additional files" maybe with a progress bar (if its too complicated maybe with just a status like Download Started/Download Complete).
If someone have good working examples pls share.