Marcin Wichary calls attention to Wakamaifondue’s excellent file dropping experience—you can drop it anywhere and it’s accepted:

Why is all this important? Because dropping a file into a browser is a notoriously frustrating experience. If the tab doesn’t claim the file, left to its own devices the browser will do anything from replacing the current tab with the contents of the file, through opening a new tab, to… starting to download the file you just dropped and ask you for its new location!

I ran into this very problem today in Micro.blog. Wakamaifondue gets it right and looks good doing it.