Prevent NPE

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35768 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Force openGL to restart when refresh views

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@35769 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e