don't disable buttons from header

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36630 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#4541 - fixing cas rtl

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36631 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
use getPlain for delete

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36632 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
typo in method name

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36633 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
#4574 - fix

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@36634 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e