Key sequence to override current page's built-in shortcut and let DeadMouse have its way

[chetan51]

Some websites (including GitHub) have their own keyboard shortcut scheme. DeadMouse doesn't disable those shortcuts, but those shortcuts can get in the way of using DeadMouse. So it would be nice to have a key sequence that DeadMouse watches for to jump in a override the page's shortcuts, until it's done following a link.