The selection indicator is just a drawing. You can override the drawing of the selected row with CellBackgroundPaint. I've done just this in my own apps. Fill a rect the size of the cell that is the color of the background of the control and return true. This will override the selection drawing.
Alternatively, you could change the selection by to -1 whenever it changes. This approach may come with unexpected behavior.
Emile, you can still use the classic API (
Listbox.ListIndex) in 2019r3 it only does not show in auto complete.