lcl: gtk2: clean up

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41657 4005530d-fff6-0310-9dd1-cebe43e6787f
lcl: gtk2: disabled gtkwidgetdraw when updating the LCL

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@41658 4005530d-fff6-0310-9dd1-cebe43e6787f