A button that runs its own progress - start it and a stop button buds off its side like a droplet, then melts back in when the work ends.
A button that shows its own progress, with a stop button that buds off its side while it's working.
The stop button was inside the pill the whole time. Behind the label sit two plain shapes, the pill and a circle tucked under its right end, run through an SVG goo filter. While they overlap they read as one body. Slide the circle out and the blur between them stretches into a neck, then pinches off into a droplet. Stopping plays it backwards.
One number does all of it: a slot beside the pill springs open and pushes the circle out. The label is "Updat" plus one of three endings, so the word rewrites itself and the pill resizes to fit.
A few small tells on top. Hover and the arrow drops through its box once. While it runs, it keeps falling. When it finishes, one ring goes out from the pill.