"Working" window should have a 'cancel' button

[themusicgod1]

It is way too easy to click on a folder to load that has a large number of files to add. Once you do this, however, the window pops up to add those files to the playlist.

example:

"Working...

file://blahblah/blah.mp3

123800 files found"

I didn't actually *want* to add 35,000,000 or 7,000,000,000 or whatever files to my playlist, one at a time, and during the time it takes to add them I see my mistake...but the only way to correct it is currently to wait for the whole thing to be added to the playlist, which will take a looooong time. In the meanwhile the window is open, it would make a lot of sense to have some kind of a 'stop this madness!!!' button.

Ubuntu: 16.04 xenial
Linux Hedy 4.4.0-21-generic #37-Ubuntu SMP Mon Apr 18 18:33:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
audacious:
  Installed: 3.6.2-2
  Candidate: 3.6.2-2
  Version table:
 *** 3.6.2-2 500
        500 http://ubuntu.bhs.mirrors.ovh.net/ftp.ubuntu.com/ubuntu xenial/universe amd64 Packages
        500 http://ubuntu.mirror.iweb.ca xenial/universe amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: audacious 3.6.2-2
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: GNOME
Date: Sun Sep 4 15:51:56 2016
EcryptfsInUse: Yes
InstallationDate: Installed on 2014-07-09 (788 days ago)
InstallationMedia: Ubuntu-GNOME 14.10 "Utopic Unicorn" - Alpha amd64 (20140708)
SourcePackage: audacious
UpgradeStatus: Upgraded to xenial on 2016-08-16 (19 days ago)