Multiple Windows

I have been using the new Github Copilot app for a few months now. It is really growing on me. One of the biggest limitations I see is the inability to have multiple windows open at once. I know that I can have multiple sessions running in the one window, but I do like the ability when using VS Code or Github Copilot CLI I can have multiple windows open if I'm working on multiple projects.

该 issue 没有指出任何文件、测试或入口点。首先定位桌面应用如何创建和管理窗口与会话，然后明确对独立项目的预期行为。完成后应支持多个相互独立的应用窗口，但该 issue 没有定义所需的交互或验收测试。

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