Perform various tasks on your current tab.
Whenever you resize the screen, a tooltip will display in the upper right corner with the sizes of the screen and the window.
If you click the browser icon, your current tab will turn into a popup window.
If you press Alt+P, your current tab will toggle between being pinned.
If you press Alt+K or Alt+J, the last number in the URL will increment or decrement (e.g. "page01.htm" becomes "page02.htm").
If you press Alt+Y while on YouTube, it will toggle between an embedded (pseudo-full-screen) video.