GUI: Refresh in Operator Panel - Graph Viewer properties
When changing the Type field in the Graph viewer, the Sample value
becomes invalid only after closing and reopening the Graph Viewer.
After changing the Type, the Sample value also can only be changed after
closing and opening the Grah Viewer. If I do not close and reopen the
Graph Viewer, it complains that type and Sample type do not fit
together.
(from redmine: issue id 2058, created on 2014-07-21, closed on 2015-07-30)