Please describe the problem:
gThumb gets confused if I open an image, make some modifications, try to view the next image on the folder, first choose save as and then cancel on the file name dialog when gThumb asks if I want to save my modifications. After this the Next and Previous buttons stop working. Additionally, if Close button is clicked and any image on the folder is chosen to be viewed, the modified image is shown instead. 

Steps to reproduce:
1. open a file 
2. do some modification, e.g. image/desaturate
3. click 'next' button to view the next image in the current folder 
4. gThumb notes that the current image has been modified and asks if you want to save it. Click 'save as'.
5. click cancel on the file name selection 

Actual results:
As described above.

Expected results:


Does this happen every time?
Happens every time.

Other information:
I'm using gThumb 2.10.6 distributed with Ubuntu Gutsy (7.10).