IDE: component list: update buttons on becoming visible

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46588 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: clean up

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46589 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: component list: update buttons

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@46590 4005530d-fff6-0310-9dd1-cebe43e6787f