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## Summary of the Pull Request
This is the spec for the Advanced Tab Switcher. This would allow the user to navigate through a vertical list of tabs through a UI, similar to those found in VSCode and Visual Studio.
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## References
#1502: Feature Request: Advanced Tab Switcher
#973: Ctrl+Tab toggling between two tabs
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## PR Checklist
* [x] Spec for #1502
* [x] CLA signed.
