Header/mode line is resizing the windows

[jcubic]

Related to:

• Header/mode line is not clickable #448

When you have vertical split windows, you can't click on the header UI because it triggers a resize, and it also has a vertical resize cursor.

Steps to reproduce

• Call C-x 2
• Run Agent-shell in the bottom window

Checklist

• I agree to communicate with the author myself (not AI-generated).
• I've read the README's Filing issues section.
• I'm running the latest versions (fill in below).
  • agent-shell version: 20260408.1635
  • acp.el version: 20260325.1158
  • ACP package (e.g. claude-agent-acp) version: 0.30.0
  • Agent CLI (e.g. claude, gemini) version: Claude Code
  • LLM: Opus 4.6
• For requesting new agent support, I'm including a link to the ACP-capable agent or related ACP package.
• For issues, I'm including ACP traffic (as per README).

[xenodium]

Thanks for filing.

Not sure there's much we can do here. This may be an Emacs limitation. Happy to consider suggestions.

Maybe look at M-x window-divider-mode and see if that helps?