styles of buttons in MaterialListElement

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37347 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
style of cursor

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@37349 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e