I'm fairly sure the TNotebook has this in the Options, but as you say it would be good for TTabsheet and TPageControl as well.
I've tried what you've mentioned. But it looks like TNotebook's close button property is not working for me.My platform is
Win XP, Laz. 0.9.29.22078 fpc 2.2.4. ( not a stable version)
However I've also tried in the stable version but it didnt work also.
Can you please test it? I dont want to put a post to bugtracker until I am sure.
Thanks for the reply.