即使选项卡组中有多个 windows，NSWindow 选项卡栏也会隐藏

Question

I'm trying to add tabs to an old codebase, and followed along the documentation. But the tab bar remains hidden, even with multiple windows in the tab group: The menu Window > Show Previous Tab and Window > Show Next Tab work as expected.

With a breakpoint after:

self.window?.addTabbedWindow(newWindow, ordered: .above)
newWindow.orderFront(self.window)
newWindow.makeKey()

The tab bar is visible, until I continue the breakpoint.

Inspecting the NSWindow.tabGroup.tabBarVisible before and later also has the tab bar set as visible.

Answer 1

Turns out the tab bar is implemented as a NSTitlebarAccessoryViewController and is part of the NSWindows.titlebarAccessoryViewControllers .

The problem was we also used a NSTitlebarAccessoryViewController in our app, and removed it by iterating all NSWindows.titlebarAccessoryViewControllers and removing each one.