bugfix: can get wrong cursor when <Shift> held

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23216 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
CAS editor skeleton

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23218 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e