Ticket #3825: fix for the CAS view click cell bug

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30142 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
We can select a cell with a click on a row header too. (#3530)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30143 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e