How can I save all modified files in Preview in one go? When I open several images in preview and apply quick modifications in succession I would like to close preview and save all the files without questions. Unfortunately preview keeps asking for each modified file if I want to save it or restore the original. Which is  anyway quite useless because it only offers the name instead of showing what image is the question about.

The only quick and manual way I've found is to use the keyboard shortcuts for save + close window in quick succession. But this is quite tiresome. I was hoping there is a "save all" but can't find anything like that in the menus. Can all files be saved without the annoying question?
Appearance Control Panel in System Preferences



I believe you may find what you are hoping to accomplish by checking here, which describes how to disable the autosave function, which is not what you are looking for... but in the top most screenshot is the Appearance Control Panel (/Applications/System Preferences.app/Appearance Control Panel) there is a checkbox to utilize the builtin autosave features of Lion, Mountain Lion, and Mavericks. Find that control panel and uncheck "Ask to keep changes when closing documents" and see if that does what you want.