Summary

The client-side rsel drag selection (blue overlay, pwsh-style) has a few behavioural gaps compared to Windows 11's native PowerShell selection in Windows Terminal:

1. Pane boundary bleed: the overlay spans the full terminal width on intermediate rows, so dragging inside a pane visually bleeds into neighbouring panes on multi-line selections.
2. Forced copy-on-release: rsel always copies to the clipboard and clears the selection on mouse-up. Windows 11 PowerShell keeps the selection visible until an explicit copy action (right-click, Ctrl+C, Ctrl+Shift+C), letting users refine the selection or dismiss it with a click.
3. No multi-click word/line selection: double-click / triple-click do nothing special. Native terminals expand to a word / line.
4. No modifier-extend: Windows 11 uses Shift+click to extend an existing selection — unfortunately Windows Terminal reserves Shift+click for its own native selection override, so this needs a different modifier (Ctrl+click is a natural fallback).
5. No block selection: Alt+drag does not produce a rectangular selection.
6. No Ctrl+Shift+C / Ctrl+Shift+V / smart Ctrl+C bindings tied to the rsel state.

Item 1 is a latent rendering bug (intermediate rows iterate 0..=area.width-1 regardless of pane rect). Items 2-6 are behaviour the existing rsel path was never designed for but are expected by users coming from Windows 11 PowerShell.

Proposal

Add a new pwsh-mouse-selection session option (boolean, default off) that opts into Windows 11 PowerShell-parity behaviour:

• Pane-aware clipping (fixes pwsh is not default installed #1 for anyone with the option on)
• Selection persists after mouse-up; copy only on right-click / Ctrl+Shift+C / smart Ctrl+C
• Double-click word / triple-click line selection (within the originating pane)
• Ctrl+click extends the current selection to the click point
• Alt+drag produces a rectangular (block) selection
• Ctrl+Shift+C, Ctrl+Shift+V, and smart Ctrl+C (copy-if-selected, SIGINT otherwise) key bindings
• White overlay (closer to Windows Terminal's native selection colour)

Default stays off so existing users see zero behavioural change.

Environment

• psmux version: 3.3.2
• Terminal: Windows Terminal
• OS: Windows 11

Notes

• Shift+click cannot be reclaimed because Windows Terminal hardcodes it as a native selection override regardless of mouse tracking state. Ctrl+click is used instead.
• Auto-scroll during drag at pane edges is out of scope — rsel operates on visible content only, and scrolling the scrollback buffer belongs to copy mode.