One further question for VirtualMode layout.
What Schmidt suggested for the FlexDataSource interface means actually always 1 fixed row (field name) and 0 fixed columns.
The GetFieldCount method would define the number of columns and the GetRecordCount the number of rows.
However, that means I also need to disable the Rows/Cols and FixedRows/FixedCols properties.
OR instead they are allowed (flexible) and just a 'RetrieveVirtualItem' event would be fired for all cells in viewport, regardless if they are 2 fixed rows or none. I think that would be a very flexible approach?