Capsules are the new new new thing
Before OS X, the common shape for Mac buttons was rounded rectangles.
The new thing
Then, in early versions of OS X, the new thing for buttons was the capsule shape—as you still see in dialog and sheets, for instance.
The new new thing
Then, with the iApps and Safari, the new new thing was rounded rectangles.
But—think about it—aren’t you getting just a little bit tired of the rounded rectangles?
The new new new thing
Though Tiger has lots of rounded rectangles, it appears to me that the new new new thing is the capsule shape. There are differences, of course:
1. They tend to be flatter—they aren’t as 3-D as OK and Cancel buttons, for instance.
2. They use either a single gradient—or they use that two-gradient glass look (that you see in many other places and is itself a trend worthy of note).
(You do still see plenty of rounded rectangles, especially for objects that aren’t exactly buttons—the line of Dashboard widgets at the bottom of the screen, for instance. A capsule shape doesn’t work that well when the rectangle is a square.)
What is most interesting to me about the current capsule buttons is that we have competing visions: single gradient vs. glass look. Note for instance these two Save buttons, one from the Finder and one from Mail. The Finder button uses a gradient, while the Mail button uses the glass look (which it also uses in its toolbar buttons).
(It’s as if hemlines have shortened a bit this year—but both basic black and floral prints are in style.)
Also interesting is that the Finder is using the capsule shape with popup menus. I don’t recall ever having seen that before. I quite like it.
(We almost used this same widget in NetNewsWire, by the way: it would have been in the header cell above the subscriptions list; it would have allowed you to choose the sort order. We decided against it for reasons other than the appearance of the widget itself. [Our version was smaller than the widget shown above, to better fit that space.])
Rounded rectangles will be back, probably some time next year. But there will be something different about them that I can’t predict. (Flatter? Less flat? Or...?)
But, right now, capsules are the thing.