QuerySeeking doesn't appear to work
Attempting to use a QuerySeeking query results in "gst_query_set_seeking: assertion 'gst_query_is_writable (query)' failed".
I've tried QueryPosition and QueryDuration and they work fine but QuerySeeking appears to refuse to work specifically due to doing a const cast on the query in Gst::Element::query(). If you don't const cast it then the seeking query is fine.
I discovered this anomaly when I translated the gstreamer c "basic tutorial 4" into the c++ of gstreamermm. I've attached that translation to demonstrate the problem.queryseeking_issue.tar