canvastest: Further improves syscolor test

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46173 4005530d-fff6-0310-9dd1-cebe43e6787f
cocoa: Improves syscolors which fixes the look of TBevel

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46174 4005530d-fff6-0310-9dd1-cebe43e6787f