@Andy B Even better if the IDE would "grey out" or otherwise let you know that there's no point in changing that value, depending on the platform chosen.
I don't disagree with you Andy, but I think because some native controls can look and behave differently between versions of a given target platform, e.g., Windows 7 vs. 10 or High Sierra vs. Catalina, that might be a bit too much to expect of the IDE.
Like that old slogan, from another language, "Write once, run anywhere" eventually was repeated as "Write once, test everywhere".
Besides, for the some of the important things, the Xojo documentation is pretty good about pointing out where something doesn't work for a specific platform. See ToolbarButton.ButtonStyles as an example.