For those who read Gmail via its Web interface, including in Mailplane, Google has released a Gmail Labs feature called Preview Pane. It gives Gmail a vertical interface with labels on the left, a vertical list of message summaries in the middle, and the main conversation display pane on the right. It works best with wide screens, though if you have a tall screen, you can switch it to a horizontal split instead of a vertical split. The approach is much more like Gmail’s tablet interface, and in turn like Mail on the iPad. follow link
Two Shortcuts for App Exposé
If you want to see all the windows for a particular app via App Exposé, there are two hidden shortcuts. For either, start by pressing Command-Tab to bring up the app switcher. Then, while still holding down the Command key, press either the 1 key or the up arrow. That puts you into App Expose mode, with all of an app's windows showing, and recent documents in a row across the bottom of the screen. Let up on the Command key, and then you can press Tab to cycle through all the running apps.
Gmail Gains Optional Preview Pane