Downloads in Thunderbird in Mac

If you (instead of saving them) open by double click attached files in Thunderbird, they are stored by default stored on the Desktop. This is an annoying bug . I read this workaround and I am doing something even simpler.

First, configure Thunderbird to choose as download folder /private/tmp :

This is actually tricky as /private/tmp is a folder you don't usually see. When you "choose" the folder, you hit "Command+shift+G" and in the resulting field you type /private/tmp:

Finally, configure it to "ask always" where to download (see 1st picture)

In this way, opened files by double click go to /private/tmp which is cleaned up periodically.