Is there any way to save my screen layouts across projects? I want to save my screen layouts like "Default", "Scripting", "Animation", etc. across projects. Meaning that if I update it one place, it will update across all projects (just like how changing "user preferences" works).

I know I can save a startup .blend with customized layouts. But I work on 2 projects at the same time, thus I need to sync the layouts. 

Edit: What I need is being able to change the layout in project #1. Then it would update across project #2 and project #3 as well. It doesn't have to simultaneous - it's ok if I need to reopen project #2 and project #3. But I don't wish to change layout in project #1, then make the same changes in the startup-file (thus twice the work).
In User Prefrences > File:
Uncheck Load UI

Then, your window layout will be preserved regardless of what file you open.