Here's one way to do this in DVDA - this effect looks best when you aren't using an animated background.

You build both menus: main menu and scene selection menu. Then go into preview mode and on the main menu move to your "scene selection" option but do not push enter. Set the preview quality to "best" and then click on the "copy to clipboard" icon. Bring up windows paint, and on the edit pulldown select paste; save the file out.

Repeat this process for your scene selection menu.

So you've now got 2 pictures.

Bring these pictures into Vegas and create whatever sort of transition you want between "main" and "scene" (it could be as simple as a cross fade).

Render the result to a new MPEG file.

Now, back in DVDA, go to your scene selection menu and on the background video, specify the MPEG that you just created.

Go back to your main menu and preview - now when you select "scene selection" you'll jump to the scene selection menu but the mpeg background will make it look like whatever transition you wanted.

Refinements - delayed menu buttons can be kinda cool and you can simulate this by setting the "selected button color" to none and then doing the preview/capture sequence. So you now have 3 pictures to work with. Or you can even have the buttons fade in by just getting a capture of the scene selection menu without any buttons on it (that is, just the background). When I do this I usually end up removing the original buttons from the menu and leaving an empty text box - you'll need to play with highlighting and such to get whatever effect you like.

Now, whether this looks any good or not is going to largely depend on the player. Some players will hold the last image when you transition from one menu to another; some players go to black.

Audio makes things more complicated, since you will always hear the transition, though there are ways to cover this (mainly by transitioning to some totally different audio).

It would be really nice if DVDA let you break the menu into 3 cells like DVD Lab Pro does (start, loop, end) which would let you construct very seemless transitions from a video standpoint (depending on what your video content was); maybe we can hope for this feature in 3.0.

--Scott