Toolbar

From my experience, you don't get much time to work on micro-interactions as they aren't essential to the app. As cool as they are and to implement, they don't provide much business value. However, there are exceptions.

We were designing and implementing components for a tablet app. We already had a desktop app, which we had the luxury of fitting a numerous icons and actions. But there's not much real estate to work with on a tablet. We needed to figure out a way to show as many icons and actions as we possibly could without sacrificing too many features that exist in the desktop app.

Micro-interaction became essential to our design and implementation. Users could enter a specific mode and within that mode, the top-level toolbar is replaced by the secondary toolbar. Without any animation, it's extremely jarring and confusing as this is not a common pattern that they're used to.