XP theming not working properly

[MISV]

I have a Delphi application. Here XP theming works on Win10.

Loading form/code into Lazarus and enabling XP theming in project options it only partially works.

Some parts *get* themed.

But if I have this:
TPageControl
TTabSheet
TPanel
TPanel <- Not XP themed

However

TPageControl
TTabSheet
TScrollBox <- XP themed
TPanel <- Not XP themed


Now - both of above even have further nesting, so the above is not a complete list, but it appears to be one of the main differences between where it works and not works.

What I am wondering about is if I need to set some properties differently on Lazarus for XP theming to work properly (would make sense)

i.e. I have ParentColor enabled and Color set to clBtnFace .... But I do not want the panel to use clBtnFace, I want it themed.

Can anyone point me in the right direction?