How can I get Studio 2015 to automatically insert the source text in the target segment when I arrive on an empty segment after validating the previous one?

Please note that I do not want all target segments to contain source text after pretranslation. What I want is for Studio to insert the source text in the empty segment when I arrive on this new segment and there is nothing to be found in the TM. I am not using the SDL Language Cloud for this project.

Thank you for your help!!