Shapefiles maintain a set of so-called 'visibility' flags for each individual Shape. This includes the 'selected' state and also a 'hidden' state, which can be user-specified. When the Shapefile is the in-memory version of an OGR Layer, and a call is made to ReloadOgrLayerFromSource, all Shapefile attributes (e.g. Selectable) and visibility flags are lost.
As it stands, the programmer would have to maintain an external list of the selected and hidden shapes, and attempt to restore those following the reload. This 'improvement' would build the functionality into the OCX.