GUI crashes after canceling image selection

[Sasquatch]

The GUI crashes when one wants to add a new disc to a VM, be it a CD/DVD image or a Hard Disk image, and then click on Cancel.

Steps to reproduce:

• Have a partition on your system that is not mounted
• Open VB, go to a VM settings, Storage section and add a disk of either kind
• In the browser, click on the partition that is not mounted
• Cancel the authentication prompt if any
• Select another location, like your Home folder
• Click Cancel

VB will crash. A backtrace that is produced on the terminal is attached.

This happens on Debian Sid with the Xfce4 desktop environment, but may also happen on the Gnome environment. I do not have gksu or policykit-gnome installed, which will result in an authentication error for the partition that is not mounted. The GUI will only crash after the authentication error and another location has been selected. If the file chooser is still on the partition that failed to mount, hitting Cancel will not cause a crash. Once you move away from the drive and then hit Cancel, it will crash.

[Sasquatch]

Backtrace of the crash when running VB from terminal