Cmd+A (Select All) does not work in canvas side panels on macOS

首先，在 macOS 上的 Copilot 应用中使用一个处于焦点状态的 canvas 侧边面板重现该问题，然后检查报告中描述的原生 Edit 菜单处理。完成的标准是，Cmd+A 能选中处于焦点状态的面板内容，随后按 Cmd+C 能复制这些内容，同时鼠标选择和 Cmd+C 仍能正常工作。

Short summary

Cmd+A (Select All) does nothing when focus is in a canvas side panel on macOS.

Affected version or release

Copilot app, macOS (Darwin). Version not captured at the time of the report.

Installation context

Local desktop app, canvas side panel open next to a project session.

What happened?

While viewing content in a canvas side panel, I pressed Cmd+A to select the page contents so I could copy them. Nothing was selected.

Manually drag-selecting the text with the mouse and then pressing Cmd+C works fine, so copying is possible — but for anything longer than a screen it's tedious and error-prone.

This looks like the app's native macOS Edit menu has no Select All item bound to Cmd+A, so the shortcut is never routed into the webview hosting the canvas. Drag-select and Cmd+C are native webview behaviors that work without a menu binding, which is consistent with only Cmd+A being broken.

Steps to reproduce

1. On macOS, open the Copilot app.
2. Open any canvas in the side panel that renders a page of text/content.
3. Click into the canvas panel to give it focus.
4. Press Cmd+A.
5. Observe that nothing is selected.
6. Drag-select some text with the mouse and press Cmd+C — this works, confirming copy itself is functional.

Expected behavior

Cmd+A should select the contents of the focused canvas panel, matching standard macOS behavior and the rest of the app. Cmd+A followed by Cmd+C should copy the panel's contents.

Additional context

• Platform: macOS (Darwin)
• Only Cmd+A appears affected; mouse selection and Cmd+C behave normally.
• Likely fix is registering a Select All accelerator in the app's native Edit menu so the shortcut reaches the webview.