In main now is a change that lets you edit and build individual modules
from main (or contrib) without the whole source tree. You just need
nbbuild checked out alongside them, and a binary dev build to compile
against; and for IDE usage you need a new dev build.
http://wiki.netbeans.org/DevFaqOrphanedNetBeansOrgModulesNot currently all that useful since there is not yet a straightforward
way to get sources for selected modules without checking out the whole
Hg repository - but that should be solvable, e.g. by offering individual
module sources for download as ZIPs, or by publishing a r/o SVN mirror
of the main and contrib repositories. This could make it easier to
develop casual patches against a module or two.