Start / Pause Button Fade In / Out

[Vadoola]

In Pomotroid as the Start / Pause changes state, the button fades out, then back in. Right now this doesn't happen in Tomotroid. I was initially trying to figure out a way to do it using the animation States. However since the States are from 100% Opacity to 100% Opacity, nothing gets animated.

I should be able to do what I want with a Sequnce of States, which is not yet implemented in Slint. It would be nice to add this in using a sequence of states, but at the moment, while that issue is open, it doesn't look like it's really being worked on.

In the meantime to implement this effect I could mimic it by having 2 stacked buttons, and hide one as needed, and fade them in and fade them out with a delay. That should create the same effect. I just haven't done this yet, because it's cosmetic and I wanted to get the most of the rest of the code working first.