A tab's toolbar is designed to show the basic information related to that tab. We strongly seek to avoid clutter here, and generally start by assuming that we wouldn't include something unless it had a reasonably high usage level.
Standard browser back and forward buttons. You can access session history in each direction by clicking and holding or clicking and dragging downwards.
A standard reload button. Ctrl and Shift do not modify this button's behavior.
When a user has enabled the home button, it appears here. The home button does not appear by default because in a multi-tab world, we believe that the bookmarks bar is a better place for navigational items.
See Bookmarks. The star may be dragged as a URL to create links to the current page in specific locations (Desktop, Bookmarks Bar).
The go and stop buttons are typically not frequently used in browsers. However, they are frequently essential (for example, the go button is useful in mouse-only situations). These buttons are combined so that while a navigation is in progress, the button shows a stop icon, otherwise it shows a go button.
If the navigation state changes while the user's mouse is over the button and the state change is not a result of a user action, the button will not change. It also protects against double-clicks.
This is generally equivalent to "File / Edit / View", and contains things contextually related to the current tab.
This is the "Tools / Options" menu, and contains items related to the browser. Technically it should be located outside of the tab bounds, but there was no satisfying way of doing so.