macOS Tahoe Tab Bar

[thecoolwinter]

Description

Updates the tab bar for a new glass/capsule based design for macOS 26. This change is not retroactive and only affects CodeEdit running on macOS 26.

The new design does two things primarily:

• Tabs are now embedded in a glass container capsule.
• Tabs are themselves glass, and are also capsule shaped.

This changes makes the tab bar look at home on the new bubbly, liquid design of Tahoe. Tabs are still draggable, selectable, etc, they're just a little more prominently in their own container.

We are not going to change our tab behavior to match Xcode, and this PR reflects that. Tabs still act the same way as they have in Sequoia, this is purely a design change.

Tab content also still appears to slide underneath the toolbar. However due to the greater opacity of the toolbar, the split view was updated to be aware of the safe area and only draw where necessary. Alternatives were considered, such as trying to make the editor itself bleed over into the safe area, but due to SwiftUI limitations for escaping safe areas this was the best option I could find.

Related Issues

• closes ✨ XCode 26 style tabview #2123
• 🐞 macOS Tahoe Workspace Window #2117
• Liquid Glass Effect Can't Disable Backgrounded State #2129 - related, and commented on in code

Checklist

• I read and understood the contributing guide as well as the code of conduct
• The issues this PR addresses are related to each other
• My changes generate no new warnings
• My code builds and runs on my machine
• My changes are all related to the related issue above
• I documented my code

Screenshots

Split tab panes with new tab bar design.

Some tab styles (selected, hovered, scrolled under container).

[jacob-carlborg]

On the big screenshot, on the tab with the title CodeEditApp.swift, I think Swift icon is very close to the left edge of the tab. Perhaps some more space between the icon and the left edge (padding or whatever it's called)?

[thecoolwinter]

On the big screenshot, on the tab with the title CodeEditApp.swift, I think Swift icon is very close to the left edge of the tab. Perhaps some more space between the icon and the left edge (padding or whatever it's called)?

Sorry it's not obvious from the screenshot but I have that tab bar scrolled slightly off to the right to show the edge shadows on both sides. The other two tab bars are better examples of the spacing.