onEdgeLock
Called when the given edge may become locked. This can happen if an edge drag was preliminarily rejected before beginning, but after onEdgeTouched was called. This method should return true to lock this edge or false to leave it unlocked. The default behavior is to leave edges unlocked.
Return
true to lock the edge, false to leave it unlocked
Parameters
edgeFlags
A combination of edge flags describing the edge(s) locked