Default file upload folder

I am happy that FF 'remembers' where I like to put my downloaded files 
(usually in my \download\ folder) so that I don't have to work my way around 
the folder tree every time.

I think it would be an improvement if I could also choose a default folder 
from which I upload files to websites such as Facebook and exercise logging 
sites. I find it quite irritating that the file upload dialog always starts 
at the 'desktop' from which it takes several clicks to reach the file to be 
uploaded.

In short: I want to be able to choose the defauilt folder for file uploads.

Are any FF developers reading this? Do you think that's a reasonable request?

R.