Nezchan, Interesting. Playing around with the #Tuba client for Mastodon, and the "add media" thing is busted. If I try to add a photo or whatever, the file choosing window tries to come up but does not display any contents, then fails after a few moments.
I also cannot drag and drop from my file browser.
The only way I can add images is to CTRL-C either from a web page or local image viewer, and then paste them into the Media tab. Which is awkward, but at least it works.
Bugs will be bugs I guess.