I'd like to request that there be an upload dialogue for uploading art assets somewhere in the program (this is how the deck builder works). The logical place would be in the art library manager.
I tend to run Roll20 fullscreen, and so its usually more work for me to open up a file browser, set it to 'always on top', navigate to my files, and drag/drop them in than if I could just do it inside the program. Furthermore, I've had problems getting the drag and drop functionality to work at all with Firefox under Linux (it works fine with Chrome, but in Firefox it tends to go to another page and displays the image rather than uploading it).
In part this is just a matter of taste as far as preferred usage, but I figured I'd ask anyhow.