Startup Disk Creator silently fails to select an image it cannot read

[Otus]

When trying to select a file for which I don't have read permissions, Startup Disk Creator fails to select it, but gives no information on why. Only by launching from the terminal do I see the reason:

isoinfo: Permission denied. Cannot open '<snip>'. Cannot open SCSI driver.
isoinfo: Permission denied. Unable to open <snip>

(This happened to me because virt-manager silently changes the owner and permissions of any .iso files it uses. I had no idea about the problem before I resorted to using the command line.)

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: usb-creator-gtk 0.2.50
ProcVersionSignature: Ubuntu 3.11.0-13.20-generic 3.11.6
Uname: Linux 3.11.0-13-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
Date: Thu Oct 31 11:48:24 2013
InstallationDate: Installed on 2012-11-10 (354 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
MarkForUpload: True
SourcePackage: usb-creator
UpgradeStatus: Upgraded to saucy on 2013-10-18 (12 days ago)