Possible fix for #3929 (NPE at creating combobox). Just for the desktop version.

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30783 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
line equality testing change

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@30784 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e