LCL: docs

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42500 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: source editor: pagechanged event when creating the first page

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42501 4005530d-fff6-0310-9dd1-cebe43e6787f