http://bugs.winehq.org/show_bug.cgi?id=49055 --- Comment #4 from realmaitreal@deadmail.lat --- (In reply to Stian Low from comment #3) Thanks for running it. Combining your result with a re-run here on stock wine, I need to walk back part of comment #2. I re-ran the attached testcase on stock WineHQ-devel 11.14 -- not the fork from comment #2 -- with a fresh prefix, on macOS 26.5.2, Apple M2 under Rosetta: x86_64 renderer=gl csmt=0x1 4 failing (4 runs) x86_64 renderer=gl csmt=0x0 4 failing (1 run) x86_64 default (picks gl) 3 failing (1 run; the ~1-in-8 flake) x86_64 renderer=vulkan csmt=0x1 0 failing (4 runs) i386 renderer=gl csmt=0x1 4 failing (2 runs) So CSMT is not the variable -- it fails with csmt on and off. The renderer is: GL fails deterministically, Vulkan is clean. On GL it is the same four cases every time, the ones where the render target is an additional swapchain's back buffer and a Present has happened. That bears on whether this testcase belongs on this bug at all. This report is x86-64 Linux, and if GL genuinely passes there, then what I attached is a macOS GL bug rather than the cause of the black screen reported here, and it should move to its own report. The reasoning in comment #2 was a plausibility argument from WPF's use of CreateAdditionalSwapChain; it was never direct evidence that this particular clear behaviour is what breaks WPF on Linux. Before I split it off, one check on your port, since it decides the question: does it create a fresh HWND for each of the sixteen cases? The standalone testcase builds a new window and a new device per case, and reusing either one masks the failure here -- all sixteen then pass. If the visual.c port shares a window, the Linux GL run is inconclusive rather than a genuine pass, and the attribution may still stand. If it does already use a fresh window per case, I will move this to a separate macOS bug and stop cluttering 49055. -- Do not reply to this email, post in Bugzilla using the above URL to reply. You are receiving this mail because: You are watching all bug changes.