No, each layout is a separate design in FileMaker. In FM12 it is possible to create cross-layout "guides" which make it very easy to copy/paste and align items from one layout to another, but the object(s) have to be added to each layout as desired.
In the long run, having a universal layout part/object might be counter-productive when layouts have widely differing uses, such as reports, forms, etc.
Try using fields as your buttons. Then attach a script to the button that determines what script to run based on the value in the field. That way once you change the value in the field it will change across all layouts.
Another option is to use merged variables or merge fields on top of the buttons. Each button has a script parameter that you can use to determine what script to run.