(Congratulations on the Flow alpha release showing off your fine UX work!)
Some users somewhere said that the Full view - Collapsed view - Small view trio of icons on Flow boards don't act like buttons. They're currently "dead" apart from the cursor change.
They seem to me like quiet action buttons such as Cancel, that don't have the border and beveled bottom of CTA buttons. So like Cancel they should have a mouseover state.
But I notice that quiet Cancel in Flow has no mouseover state, while it does have an undocumented click state which lightens to something that looks like a disabled state... but Cancel has no disabled state.
Also I recall May and Juliusz at the UX hack #3 deciding to flip the normal and mouseover state so you can see the neutral/progressive/destructive/constructive colors of quiet buttons by default, even on a tablet. But Agora Control Library says the opposite, "Button with Neutral null state and Progressive/Destructive/Constructive hover, click, or post-click state"
We need a more definitive Agora button spec with all four states (normal, mouseover, click, disabled) for both quiet action buttons and CTA buttons, for all four types (neutral/progressive/destructive/constructive). 32 flavors! Or 40 if "post-click state" is an additional state.