Such as in the games, before transitions the background and sprites usually fade away to black, and then the next scene fades in.
Maybe it'd be an option the screen editor "Fade frame in" or something like like that, and it'd just fade itself ontop of the previous frame? (So if you wanted it to fade out, just make the next frame "Black Background" and have it fade in").
And music fade in/out would be pretty amazing as well. It's always awkward just having music "stop" instead of fading, especially with objection and pursuit themes.
I had an idea that if in the "Music" tab, if two tracks used the same music file (Let's say they're both Objection 2001), and while one has volume set to 100, the second has it set to 0. In the trial editor, if you had the first one at Vol. 100 playing for a few frames, and then you switched the music to the volume 0, it continues to play but it slowly changes to the new volume. This way, you could have the music continue to play in the background but not audible, so if it could just fade in at the point it would have been if it kept playing (Ex. Cross Examination-
- find contradiction, objection theme plays, prosecution gives rebutting argument and objection theme fades away, defense fights back that argument and the theme fades back in at where it would be if it kept playing, or cross examination- 
- witness says something serious/very important and the music fades away, after the conversation about said serious/important thing is finished the cross examination music fades back in where it would be if the music kept playing.)I bet you guys are already trying to implement a fade system but yeah