Make a new layout with the selected theme. Copy in the inspector (tab appearance) the object style and paste the style on the selected items.
Thanks for your reply. Sorry, I should have stated that I am aware of the workarounds. I was hoping for a more direct approach such as a special key combination that can be used when you select the theme.
Not aware of any such option.
The intent of applying a theme is to give a uniform look to the whole layout. It appears to be an all-or-nothing option at the moment, until you customize specific objects after applying the theme.