I forgot to say that I know I am supposed to use Alphacontrol sPagecontrol, but it would be too much work to recreate all the existing Delphi TTabsheets (because they have lots of existing controls which I need for the rest of the project and I do not have not have to display these existing controls)
So I simply want to continue to use regular Delphi TabSheets but use Alphacontrol sPanel to display the Aluminium background. Then I will only display the Delphi Tabsheets that have an Aluminium background.