This thread is particularly about how the S3Engine 2.0 deals with UI.

We've chosen to implement the menu system with native Win32 menus, with a slight twist.

When running in windowed mode, the menu bar is always visible; when in
fullscreen mode, the menu bar is hidden, but when you mouse over where it should be it appears.

We use common dialogs in all appropriate places as well, for loading and saving as well as dialog messages.

The use of native UI was a complex decision, in many ways it gives the best of many worlds.

Pros:
-Native UI fast and well tested
-Native UI is easy to develop
-Native UI has advanced features (ability to save and load from network sorces, etc.)
-Our hybrid fullscreen methods help keep immersion
-Native UI provids a familliar interface to windows users
-You can paste a serial key from the clipboard in native UI

Cons:
-Native UI just isn't as flashy or animated as custom UI (this is the big tradeoff, but less of an issue in Vista)

Overall the decsion was to sacrifice a bit of custom visual appeal, for a ton of functionality; we felt that people could get over fairly typical menus in exchange for a less frustrating user experience.