Why does the scrollbar of a TListbox disappear behind a tabsheet. It is already visible in the designer. In the next example a simple button toggles the visibility of a listbox. When it gets visible it is displayed over the tab, but the part of the vertical scrollbar that should overlay the tab get invisible.
I include a simple example demonstrating the effect.
I tried a view things (as BringToFront, SendToBack), but nothing seems to help.