Let's imagine I have the covers explorer opened in Calibre.
And let's imagine after downloading the Metadata I cannot find the cover of my book (thing that happens normally when you are in other languages in which the covers are not widely distributed, for example, spanish).
What I would like is, after searching the cover in Google
Drag it to Calibre
Drop it in Calibre
I have the cover placed properly in the book
Drag and Drop covers
I think this feature would be great to incorporate in new versions