[FEATURE] Desktop app: Open a new session directly in split view (Alt+click on "+")

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

In the Claude Code tab of Claude Desktop, I can view two existing sessions side by side by Alt+clicking a session in the sidebar. However, there is no way to open a new session directly into the split view.

When I click "+" next to a project (or "New session"), the current view is replaced by the new session, and Alt+clicking "+" does not open it in a split pane either. When running parallel tasks on the same project, I often want to start a new task while keeping an eye on the session that is already running, and the current behavior makes this awkward.

Proposed Solution

Alt+clicking "+" next to a project (or "New session") should create a new session and open it in a second pane alongside the currently open session, keeping the existing session visible.

If a split is already active, the new session could replace the focused pane, consistent with how clicking a sidebar session behaves in split view today.

Alternative Solutions

Current workaround:

1. Click "+" to create a new session (the view switches to it)
2. Send a first message so the session appears in the sidebar
3. Alt+click the original session to bring it back as a split pane

This works, but it takes several extra steps every time I want to start a parallel task.

Priority

Low - Nice to have

Feature Category

Other

Use Case Example

Example scenario:

1. I'm working in a PHP project, and one session is running a long task (e.g. a code migration).
2. While it runs, I want to start a separate task in the same project (e.g. fixing an unrelated bug).
3. With this feature, I could Alt+click "+" and start the new session right next to the running one, so I can monitor both at the same time.
4. This would save me from repeating the create → send message → Alt+click workaround every time.

Additional Context

• OS: Windows 11
• Claude Desktop version: (Claude 2.26454.0 (98e3cc) 2026-10-06T05:51:15.000Z)

Related:

• On Windows, the documented Ctrl+click for split view doesn't work as expected (#55764); in my version, Alt+click is what opens a session in a split pane.

<img width="1356" height="518" alt="Image" src="https://github.com/user-attachments/assets/931a2e82-2b28-4e14-864b-cf4f7581a5ba" />