In gThumb imageviewer, press/releasing right mouse button while doing click/dragging over a photo at actual size, causes system crash

[apostle]

ubuntu 13.10 desktop i386
gThumb 3.2.4

ISSUE
In gThumb image viewer, press/releasing the right mouse button while doing click/dragging over a photo zoomed at actual size, causes the system to freeze.

STEPS
1. open an hi-res picture with gThumb image viewer
2. press "1" or "z" or "/" (numeric keypad) to zoom the picture at actual size
3. press mouse left button and start dragging on the picture
4. while dragging, press and release the mouse right button
5. stop dragging.

EXPECTED RESULT
Nothing.

UNEXPECTED RESULT
The system becomes unresponsive.
To get back to system functionality, one has to exit gThumb through keyboard shortcuts (i.e. pressing "CTRL + Q").