This isn't really a -huge- issue but more of a minor annoyance. I was wondering if you could adopt more standard spelling conventions for your commands. I am aware you're from the UK and that words are generally spelled differently over there but sometimes it can be a confusing pain..
i.e Colour reads OK for me, but Centre vs Center just drives my eyeballs insane.
From a technical aspect I would argue that Programming Languages etc that are developed in English tend to define their keywords using American / "International" English spellings. (I don't think I've ever encountered British English personally, and I can't say I've found a foreign language / API / etc but I wouldn't be surprised if they did exist).
I also realize that you may have done this, to have your own Commands that work with ProGUI widgets, that don't clash with already defined PureBasic commands; but I would have gone with a prefix in that case (ProGUI_MakeColor, etc).
Personally this is where PB falls down with the lack of namespace support IMHO, because then we could have simple stuff like
;// Or Even better, Switching to a Namespace manually ala Enable/Disable Explicit
MakeColor() ;// ProGUI command not PB
TextGadget() ;// ProGUI command not PB
Sorry for griping, thanks for listening