Gwenview (KDE 4.8.2)

With image larger than the gwenview viewing area, in zoom-to-fit mode, when crop image, the crop option bar appear, the viewing area is scaled down, and gwenview take time to re-render image.
If I don't want to crop, escape the job. And, the crop bar hides, gwenview re-render the image again.

My opinions:

* place crop options in the tool bar (inactive (gray) when not using it).
* floating dialog like in Photoshop, Gimp.

I think a better solution would be to actually improve Gwenview rendering speed. Adding inactive items to the toolbar leads to a cluttered UI, and floating dialogs gets in the way when it comes to cropping.

I don't know how it's fast when images becomes larger and larger

Also, the crop bar is not convenient for wide screen.

How about mimic the GIMP behavior, 'Double Click' in the crop's rectangle selection area to 'Apply'!? It's easier for users, I think.

Also, Gwenview is for fast editing, so do not need 'Advance Options' to precisely specify size, positions, but, in my opinion, more visual interaction. Such as, add info of size, positions of the selection in a 'tool tip' box under mouse pointer every time the mouse move over the selection. User will know the size he want to crop.
If he want to crop more precisely, he can zoom in and tune the handles (I always do it with GIMP).

While I agree clicking in the center to trigger the crop is efficient, I think it is quite difficult to discover, much more than a crop button.
The advanced options have their use, especially the constraint ratio which makes it easy to prepare a picture to print it or so that it is nicely framed as a wallpaper.