[Katsunami]

Relevant specifications:

Windows 7 64-bit
Calibre 1.24 64-bit
Removed installation and re-installed (did not remove settings)

Steps to take:

1. Open any EPUB book in Editor (I've tested 4. 3 originals, 1 converted from AZW3.)
2. Click File->Quit.
3. The Editor does nothing. No feedback.
4. Click anything: Crash. Windows kills the program.

Additional information: the editor quits as normal when using:
- X close button
- Right-click titlebar -> Close
- System menu -> Close
- ALT-F4

The editor functions seem to work as normal, at least in the short while I've been able to use them in version 1.24.