See subj.

Reproducible: Always

Steps to Reproduce:
1. Open some image in gwenview.
2. Press the "Crop" button within the "Image Operations" panel.
3. (Optionally) Specify crop region with mouse.
4. Press Enter.

Actual Results:  
Gwenview goes one level up, now showing all images within directory of the original image.

Expected Results:  
I expected the crop to be done.
The "Crop" button at the bottom of the windows looks like the default button (see attach).
Even if it looked the same as the "Cancel" button, I'd anyway expected it to be default.

Version 15.08.2
Using:
- KDE Frameworks 5.15.0
- Qt 5.5.1 (built against 5.4.2)
- The xcb windowing system
(This happened in prev versions too.)