Down at the bottom of the screen when reading an app, you have options to mark as read, load in the browser, and switch from text mode to full HTML rendering mode.

With message handling features like reply, delete, mark as read, open, and dismiss right from the message preview, you have complete control over how you want to start talking.

Gmail Labs added two new experimental features: a "Mark as Read" button and a very basic script that warns if you write about attaching documents but you forget to actually attach them.