FadeThrough
The FadeThrough transition widget performs a simple fade between the two pieces of content by first fading to a specific colour and then fading to the new piece.

Duration
The time taken to perform the entire crossfade in seconds.
Colour
The colour to fade to.
Overlap
- If true, then the transition will start "duration/2" milliseconds early.
- If false, the current content will finish first.
- The new content will start half way through the transition.