Ticket #3707: fixed NPE (null pointer exception)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29247 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Mirroring GUI for RTL languages, part 1

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29249 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#3716: panels are not visible if the selected goes don't pass their check.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@29250 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e