Preserve pane index through reshuffle.

[claudevdm]

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[github-actions]

Reminder, please take a look at this pr: @shunping @jrmccluskey

[claudevdm]

R: @damccorm

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control. If you'd like to restart, comment assign set of reviewers

[damccorm]

Thanks!