"Y" will toggle the before-after view left/right.
<Alt>Y will toggle the before-after view top/bottom, which I find more convenient for landscape-oriented images. (<Opt>Y on a MAC)
This works in any develop context, not just in process version conversion.
Does that mean that the information for the 2010 and 2012 versions both are kept/stored by LR? So when I open a copy, I really can not know whether it is my preferred version, just in case I forgot to put my preferred version on top? I haven't been able to come across anything on this issue in the tutorials so far, but is it possible to preset LR to always open the preferred version (the one with the changes), or in other words put it on top, or do I have to check every time? (Yes, Cornelia, I will be checking out the Missing FAQ eBook you mentioned pretty soon .)
No, LR just keeps a history. So it always knows which one is the current.
You can look for yourself in camera calibration panel in develop module - or by the presence or absence of the exclamation mark in the lower right corner of develop's main window.
You can go back to any history state, also for other changes in settings, like e.g. White balance.
One of the many beauties of LR!
Fine (although I was aware of those things above)! So the procedure should be
1) Open a picture in Develop Mode
2) Click the exclaimation mark (if there is any)
3) Click "Update"
4) Copy the new settings/version to the old one (or vice versa), and - back to my original question -
5) Click "Y" to decide that the preferred version will be the one that appears (on top) the next time I open this picture?
Am I getting it? So far, I've only just found Julieanne Kosts video on this, but if someone out there could point me to a more detailed step-by-step tutorial, I'd appreciated it, as this seems to be a rather important issue in LR4:
(Did I really write "read of"?)