Docs: dragging the New button to open a session in a split pane is undocumented

**Environment:** Windows 11 Home (10.0.26200) · Claude Code 2.1.240 · desktop app on latest as of 2026-09-10

Left-click-and-**drag** the **New** button opens a new session in a split pane. This works, and it appears to be the only way to get a *new* session into a second pane. It is not documented.

https://code.claude.com/docs/en/desktop describes these as two unrelated actions:

> "Click **+ New session** in the sidebar, or press **Cmd+N** on macOS or **Ctrl+N** on Windows, to work on multiple tasks in parallel."

> "To view two sessions at once, hold **Cmd** on macOS or **Ctrl** on Windows and click a session in the sidebar. The session opens in a second pane alongside the one you already have open."

Both documented split routes (Ctrl+click, and right-click → "Open in split view") only work on sessions that **already exist**. Plain-clicking **New** takes over whichever pane has focus, so the discoverable path is: let the new session take over your pane, then re-open the original beside it — which rebuilds the split backwards and leaves the sessions on the wrong sides.

The use case: I had a half-typed message in one session and wanted a *new* session beside it to ask a side question, without disturbing the draft and without using `/btw`, because the answer was worth keeping in its own transcript.

**Ask:** document the drag gesture, and ideally make **Ctrl+click on New** do the same thing, since Ctrl+click is already the split modifier elsewhere in the sidebar.

Start at the desktop documentation page at https://code.claude.com/docs/en/desktop and review the existing New-session and split-view instructions. Document the left-click drag gesture for opening a new session in a split pane, preserve the existing platform-specific guidance, and consider the Ctrl+click request separately; the documentation is done when the new-session split workflow is discoverable and unambiguous.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.