#3503 "" fallback

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@27389 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e
Try to fix black flickering

git-svn-id: http://dev.geogebra.org/svn/trunk/geogebra@27390 23ce0884-8a58-47d3-bc5c-ddf1cd5b9f9e