In an Atom keymap config file, you may encounter something like
"ctrl-tab": "pane:show-next-recently-used-item",
"ctrl-tab ^ctrl": "pane:move-active-item-to-top-of-stack",
What does the ^ mean? The "in-depth" documentation seems to make no mention of this.
Appears (based on how it constructs a textual representation of the binding) to specify keyup. So I believe the second command you provided will trigger after releasing the ctrl key, after running the first command at least once.