On the Macintosh . . .
In preferences I have changed “Same my downloads here” to the Desktop. I have checked “Always ask me where to save files.”
When I control-click on an image, I am presented with the standard Mac dialogue box – however, it is always located at the folder “Downloads” rather than the Desktop. This is also true when I use the "Save Page as . . " command under File.
My expectation is that it should offer me up the Desktop folder.