No it is not possible by design. I quote from an older discussion about the same subject:
"we decided that a mode with autobuild on a subset of the workspace confused the notion of autobuild, which currently implies that the user needs to know nothing about builds. Our
thinking is that a new working set build, for which you can add a key binding
(or remap Ctrl+B), is close enough for the small group of users that want this
capability."
So I guess that is your best bet.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…