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new-window creates the holding window at full window size. When the original pane is a split, swap-pane resized it up to the window size and back again on return. Full-screen TUIs such as nvim re-laid out their splits twice and did not always repaint cleanly, which left the pane garbled after a jump. Size the holding window to the pane before the swap, so the pane keeps its dimensions and never gets a SIGWINCH. Also force a redraw of every client on restore. swap-pane repaints only the region tmux thinks changed, and some terminals (Windows Terminal) were left showing stale cells even though the tmux grid was correct. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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Problem
Invoking flash on a pane running a full-screen TUI (nvim) leaves the pane garbled after the jump. A plain shell pane is fine.
Two causes:
1. The pane gets resized.
new-window -dcreates the holding window at full window size, not pane size. When the original pane is a split,swap-paneresizes it up and then back:nvim re-lays out twice in quick succession and does not always repaint cleanly.
2. No client redraw on restore.
swap-panerepaints only the region tmux thinks changed. On some terminals (Windows Terminal) the client is left showing stale cells even though the tmux grid is correct — verified withcapture-pane, which comes back byte-identical to the pre-flash content.Fix
Size the holding window to the pane before the swap, so the pane keeps its dimensions and never gets a
SIGWINCH.resize-window -x -ysetswindow-sizetomanualfor that window only, and the window is detached and short-lived, so nothing else is affected.Then force a redraw of every client on the session in
restore().Testing
Measured pane geometry through a full flash cycle, before and after the patch, with nvim in a split pane and in a full-window pane. After the patch the pane stays at its original size for the whole cycle. Also confirmed on the reporter's setup (WSL + Windows Terminal), where the garbling is gone.
Requires tmux >= 2.9 for
resize-window.🤖 Generated with Claude Code