Gets or sets the Leadtools.MedicalViewer.MedicalViewer control for the cell
In the ViewerCellCreating event, provide a non-default parent viewer for the cell. This is necessary because in a scenario where multiple studies are loaded by the same loader, the loader will have an invalid ViewerControl. Providing the ParentViewer in the ViewerCellCreating event allows the application to provide the correct viewer for the cell based on the study.