osx: keep window creation on-screen during display reconfiguration - #21543
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MrJul merged 4 commits intoAug 19, 2026
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WindowBaseImpl::CreateNSWindow anchors the new NSWindow's content rect to the primary screen's frame.origin. The primary screen is at Cocoa (0,0) on a healthy Mac, but can be offset (often negative) while the display server is mid-reconfiguration -- e.g. CGMainDisplayID() briefly returns 0 after wake-from-sleep -- or on multi-monitor layouts where the primary is not at the origin. Anchoring keeps the window on a real screen so it is positioned on-screen and its flipped Position lands inside a Screen.Bounds. See AvaloniaUI#18895. Co-authored-by: Cursor <cursoragent@cursor.com>
When locating the screen that sizes a new window, fall back to a default size if AppKit reports no screens -- or none whose bounds contain the last-known position -- during a display reconfiguration. The window is repositioned on the next ScreenChanged event once the display server settles. See AvaloniaUI#18895. Co-authored-by: Cursor <cursoragent@cursor.com>
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The changes look good, but please trim down the overly verbose AI comments as per our AI guidelines.
Edit: I've edited one and removed the other.
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…valoniaUI#21543) * osx: anchor new windows to the primary screen origin WindowBaseImpl::CreateNSWindow anchors the new NSWindow's content rect to the primary screen's frame.origin. The primary screen is at Cocoa (0,0) on a healthy Mac, but can be offset (often negative) while the display server is mid-reconfiguration -- e.g. CGMainDisplayID() briefly returns 0 after wake-from-sleep -- or on multi-monitor layouts where the primary is not at the origin. Anchoring keeps the window on a real screen so it is positioned on-screen and its flipped Position lands inside a Screen.Bounds. See AvaloniaUI#18895. Co-authored-by: Cursor <cursoragent@cursor.com> * osx: keep window construction resilient when no screen contains it When locating the screen that sizes a new window, fall back to a default size if AppKit reports no screens -- or none whose bounds contain the last-known position -- during a display reconfiguration. The window is repositioned on the next ScreenChanged event once the display server settles. See AvaloniaUI#18895. Co-authored-by: Cursor <cursoragent@cursor.com> * Less verbose comments --------- Co-authored-by: Cursor <cursoragent@cursor.com> Co-authored-by: Julien Lebosquain <julien@lebosquain.net>
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What does the pull request do?
On macOS a newly created
NSWindowis given a content rect anchored at Cocoa(0,0), and the screen used to size it is found with.First(m => m.Bounds.Contains(Position)). Both assume the primary screen sits at the origin and that some screen contains the window's position.During a display reconfiguration that does not hold:
CGMainDisplayID()briefly returns 0 and the primary screen'sframe.origingoes negative.In those cases the window is created off-screen, and
WindowImplBase.InitthrowsSequence contains no matching element, aborting window construction.What is the updated behavior?
WindowBaseImpl::CreateNSWindowanchors the content rect to the primary screen's actualframe.origin, so the window is created on a real screen.WindowImplBase.InitusesFirstOrDefaultand falls back to a default window size when no screen contains the position. The window is repositioned on the nextScreenChangedevent once the display server settles (the same patternX11Windowalready uses).Related issue(s)
Part of #18895. Split out of the render-timer change in #21453 per review.
Notes
macOS-only. No behavioral change on a healthy single-monitor Mac, where the primary screen is at
(0,0)and the position is contained.Breaking changes
None.