Manually Select Packages only allows you to choose which of the packages you wish to update that are offered for update.
This allows you NOT to select something that is offered as an update should you wish to do so. Why would you do this? Well it could be that the offered package will actually break something on your system. There was an instance of the gtk-qt-engine being updated which broke my installation of GIMP. I reverted to the old version of gtk-qt-engine and GIMP worked fine. Whenever updating with YOU I manually select which packages to install so that I can avoid those 'later' packages I know will cause me problems.
As far as I remember YOU doesn't do dependency checking, it just updates the installed packages to the latest security updates available. If you have extra installation sources defined (see this thread
for adding YaST sources) then maybe you want to use the dependency check ability there after updating these packages. You've obviously got some later packages ..... but not all of their requirements.
Hope this helps some way ...