LCL: gtk2: clean up

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46495 4005530d-fff6-0310-9dd1-cebe43e6787f
LCL: comments

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46496 4005530d-fff6-0310-9dd1-cebe43e6787f