make sure buttons work on tablets (just get drag events not click)

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23907 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
remove unused code

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@23908 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e