No. Themes are applied to layouts individually and they carry that theme independantly. The themes provide a starting point, ( or maybe even a changing point on a small system ) for the developer, but they do not carry over through all layouts when applied. Just the one layout at a time. So they are not meant to be a prefference for the end user to choose on the fly.
Interesting... sorry, I thought that the C in CSS stood for cascading...? I though that it would apply to multiple layouts? Ah, now I look at FileMaker 12 a little bit more, I see what you're getting at. Ok, feature request for 12 - Apply theme to multiple layouts via the manage layouts area. That would be nice.
Peter the "C" in cascading applies to parent/child styles.
If you have a paragraph (p) with the style of "color: blue;" and have a span inside of "color: red; font-weight: bold; text-transform: lowercase;". the span would get the same color (cascade) because it's a child of the p. but we've applied another color and other styles.
HERE IS A PARAGRAPH with a span WITH CHANGES
I'd rather not have ALL the layouts apply the same theme (unless they provide a scripted way to do this). I use "color-coding" on some solutions where the client has requested it. Some layouts are "blue, green, pink, etc.) based on the underlying table (invoices, contacts, etc.) These can be similar themes, but definitely different themes.
I would love to have the abilty to create and save a custom theme, build my solution, and if i decide that i would like to change the button color for instance, be able to change it in the theme and have it carry through all layouts ( or even select which layouts to apply it to from a list ). The current structure of themes in FMP 12 makes that pretty much impossible but I am interested to see how things progress from here in future versions. I also suspect we will see third party solutions introduced that are geared toward theme tools and extending the functionality of themes. We'll just have to wait and see. I'm excited about the possibilities though