A way to choose filename different from the before-upload one
An uploaded file currently uses the name it had on the uploader's
computer, with no other way to change that than changing the local
name before uploading.
That's a privacy issue, since the uploader may not expect for the
local name to become public, and will not necessarily notice it
MediaWiki uses a good solution usable with what GMG does:
after the local file is chosen but before it is uploaded, if JS is
enabled, it shows the original file name, lets the uploader edit
it, and uses the result (replacing spaces with underscores).
defect → enhancement