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## Summary of the Pull Request
Add functionality to swap a pane with an adjacent (Up/Down/Left/Right) neighbor.
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## References
This work potentially touches on: #1000#2398 and #4922
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## PR Checklist
* [x] Closes a component of #1000 (partially, comment), #4922 (partially, `SwapPanes` function is added but not hooked up, no detach functionality)
* [x] CLA signed. If not, go over [here](https://cla.opensource.microsoft.com/microsoft/Terminal) and sign the CLA
* [x] Tests added/passed
* [ ] Documentation updated. If checked, please file a pull request on [our docs repo](https://github.com/MicrosoftDocs/terminal) and link it here: #xxx
* [x] Schema updated.
* [ ] I've discussed this with core contributors already. If not checked, I'm ready to accept this work might be rejected in favor of a different grand plan. Issue number where discussion took place: #xxx
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## Detailed Description of the Pull Request / Additional comments
Its been a while since I've written C++ code, and it is my first time working on a Windows application. I hope that I have not made too many mistakes.
Work currently done:
- Add boilerplate/infrastructure for argument parsing, hotkeys, event handling
- Adds the `MovePane` function that finds the focused pane, and then tries to find
a pane that is visually adjacent to according to direction.
- First pass at the `SwapPanes` function that swaps the tree location of two panes
- First working version of helpers `_FindFocusAndNeighbor` and `_FindNeighborFromFocus`
that search the tree for the currently focused pane, and then climbs back up the tree
to try to find a sibling pane that is adjacent to it.
- An `_IsAdjacent' function that tests whether two panes, given their relative offsets, are adjacent to each other according to the direction.
Next steps:
- Once working these functions (`_FindFocusAndNeighbor`, etc) could be utilized to also solve #2398 by updating the `NavigateFocus` function.
- Do we want default hotkeys for the new actions?
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## Validation Steps Performed
At this point, compilation and manual testing of functionality (with hotkeys) by creating panes, adding distinguishers to each pane, and then swapping them around to confirm they went to the right location.
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