Automatic zoom after crop and undo is not working

[grofaty]

Pinta compiled from master on Windows XP:
1. Create new image large enough that doesn't fit on screen, so zoom will be less then 100%. In my low-resolution laptop this is e.g. 2000 x 2000 px.
2. (Observe) When new image is displayed it is displayed 30% zoom on my laptop (so less then 100%) and whole image can be seen (because of zoom). Zoom works as expected.
3. Rectangle select and select some area on canvas. Try to select as much as possible, but don't select whole image.
4. Crop to selection from toolbar.
5. (Observe) When image is cropped the zoom in my case gets to e.g. 32%. Zoom works as expected.
6. Undo from toolbar.
7. (Observe) Image is undone. Zoom is still displayed at 32%, but image is not displayed on screen, so automatic zoom does not work in this case and scrollbar appears at right site of canvas which indicates that whole image is not displayed. So after undo of cropped image automatic zoom to fit to window is expected, but instead zoom is not automatically executed.

P.S. I don't think this is new problem (I have seen this behavior for a while), so not a regression. Probably we can set lower importance and a milestone after 1.5.