IDE: More tweaking for build mode window

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41322 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: start to use the new build mode window by default.

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41323 4005530d-fff6-0310-9dd1-cebe43e6787f