Sheet 窗口附着面板（Sheet） macos
A modal panel attached to one macOS window rather than the whole app
只附着于单个 macOS 窗口、而非整个 App 的模态面板
Delete “Q3 Report”?
Blocks only this window.
标本可交互 —— 点点看。Specimen is live — try it.
Anatomy — every part, named解剖 —— 每个部件的名字
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1 Dimming layer变暗层
View.sheet(isPresented:content:)“The darkened area behind the sheet” is the dimming layer that marks the parent surface as temporarily unavailable.
“Sheet 后面变暗的区域”就是变暗层，表示父界面暂时不可用。
Prompt fragmentPrompt 片段the sheet's dimming layer (View.sheet(isPresented:content:)): the translucent dark overlay over the blocked parent surface behind the presentation
Sheet 的变暗层（View.sheet(isPresented:content:)）：覆盖在被阻挡父界面上的半透明暗色遮罩
Prompt — paste into your agentPrompt —— 直接粘贴给你的代理
Present this as a window-modal Sheet with NSWindow.beginSheet(_:completionHandler:) (SwiftUI: View.sheet), visibly attached beneath the parent window's title bar. Block only that parent window, not every window in the app.
用 NSWindow.beginSheet(_:completionHandler:)（SwiftUI：View.sheet）把它呈现为窗口级模态的 Sheet，视觉上附着在父窗口标题栏下方。只阻挡父窗口，不要阻挡 App 的所有窗口。
Debug prompt — when it misbehaves调试 Prompt —— 当它不听话时
Debug my macOS sheet (NSWindow.beginSheet(_:completionHandler:), SwiftUI View.sheet). Rule out: the isPresented/item binding never reset so it will not present a second time; endSheet never called so the parent window stays blocked; presenting from a view controller detached from the window so nothing appears; two sheets queued on one window presenting back-to-back unexpectedly. The symptom:
调试我的 macOS Sheet（NSWindow.beginSheet(_:completionHandler:)、SwiftUI View.sheet）。逐一排除：isPresented/item 绑定从未复位，导致无法再次弹出；从未调用 endSheet，父窗口一直被锁；从已脱离窗口的视图控制器发起呈现，结果什么都不显示；同一窗口上排队的两个 Sheet 意外接连弹出。症状是：
In code代码里叫什么
| Framework框架 | Symbol符号 | Note说明 |
|---|---|---|
| AppKit | NSWindow.beginSheet(_:completionHandler:) | |
| AppKit | NSWindow.endSheet(_:returnCode:) | |
| SwiftUI | View.sheet(isPresented:onDismiss:content:) | |
| AppKit | NSApplication.runModal(for:) | app-modal alternative, not a sheetApp 级模态的替代方案，不是 Sheet |