Compatibility Report

• Application: Zoom Player, modern control overlay.
• Steam AppID: 492590. The actual application tested was standalone Zoom Player MAX Debug 23.00 Beta 3 build 6, launched outside Steam, not the Steam edition.
• Scope: a layered child window drawn with UpdateLayeredWindow is displayed at the wrong desktop coordinates. An independent Win32 reproducer is attached.

Testing status (updated 2026-10-05): originally reproduced with UMU-Proton-10.0-4 and GE-Proton11-7-x86_64, via umu-launcher, in a Linux VM. The Zoom Player application overlay symptoms are now also confirmed on physical Ubuntu/GNOME X11 hardware with Intel HD Graphics 4000, using UMU-Proton-10.0-4 and a fresh prefix. See the physical-hardware results and screenshots, including the ordinary-desktop versus Wine-virtual-desktop transparency comparison and a separate fullscreen observation.

Remaining limitations: an unmodified Valve Proton build, stock Wine, and Wayland remain untested. The independent C++ reproducer has not yet been rerun on physical Linux hardware; its original VM results below are unchanged.

System Information (original VM tests)

• Ubuntu 24.04.5 LTS, x86_64, kernel 7.0.0-38-generic.
• GNOME X11 session, 1280x800.
• VirtualBox 7.1.6r167084: VMSVGA, 128 MB VRAM, 3D acceleration disabled; 2 vCPUs, 4 GB guest RAM.
• Renderer: llvmpipe (LLVM 20.1.2, 128 bits), Mesa 25.2.8-0ubuntu0.24.04.4; no accelerated GPU exposed to the guest.
• Host: Windows 10, Intel Core i7-2600K. VirtualBox uses its Hyper-V/NEM backend.
• Launcher: umu-launcher 1.4.4-1, GAMEID=umu-default, STORE=none.
• UMU-Proton-10.0-4 / Steam Linux Runtime sniper 3.0.20260928.262393.
• GE-Proton11-7 / steamrt4 4.0.20260928.262390, tested in a separate copied prefix.
• No Steam-client system-information report was collected; these were non-Steam launches.

Checks

• [x] Searched this tracker for Zoom Player and UpdateLayeredWindow; no existing Zoom Player compatibility report found.
• [ ] System-update check and confirmation on the current official Valve Proton build remain outstanding.

Symptoms

The modern overlay is a WS_CHILD | WS_EX_LAYERED window owned by the player's main window. Its Win32 parent, style and GetWindowRect bounds are correct, and UpdateLayeredWindow returns success, but its pixels appear at parent-relative coordinates interpreted as desktop coordinates.

Example from the player: with the main window at (200,140), the overlay's reported screen rectangle is (205,145)-(1165,685), while its pixels appear at (5,5). Moving the main window therefore separates its controls from the player.

The player also shows opaque black regions in the modern overlay when using a Wine virtual desktop. That transparency symptom has not been isolated independently; the diagnostic below isolates positioning.

The application symptom occurs both with and without a Wine virtual desktop, on both tested runners. No video renderer is necessary: it occurs with an MP3 loaded, and the independent test only uses User32/GDI and a 32-bit DIB.

Reproduction

In the application

1. Launch the standalone build above with either tested runner.
2. Select the modern UI and place the window away from the desktop origin.
3. Reveal the modern control overlay.
4. Observe the overlay detached from its parent, towards the desktop's upper-left.

Independent C++ Win32 test

The attached LayeredChildProbe-cpp.zip contains a standalone C++ source file, a minimal manifest/resource script, build instructions, a prebuilt 32-bit Windows executable, and its recorded output. No Delphi, Python runtime, Zoom Player code/resources, codecs, media, or third-party DLL installation is required.

1. Extract the ZIP and run LayeredChildProbe.exe with your Wine/Proton runner, or rebuild it with MinGW using the commands below.
2. Observe the red/blue child surfaces above the white host window, even overlapping the console, despite their logical rectangles being inside that host.
3. The test exits automatically after 15 seconds. It prints API results to the console and writes LayeredChildProbe-output.txt when the current directory is writable. Exit code 0 means the API calls succeeded; it does not mean rendering was correct.

The supplied C++ executable was built with MinGW GCC 13-posix and verified on GE-Proton11-7. It reproduced the same coordinate discrepancy. Its imports are limited to GDI32, KERNEL32, msvcrt and USER32.

Build on Ubuntu using the distribution's MinGW cross-compiler:

sudo apt install g++-mingw-w64-i686-posix
i686-w64-mingw32-windres LayeredChildProbe.rc -O coff -o LayeredChildProbe.res.o
i686-w64-mingw32-g++ -std=c++11 -Wall -Wextra -Werror -O2 -static -s LayeredChildProbe.cpp LayeredChildProbe.res.o -o LayeredChildProbe.exe -lgdi32 -luser32

These build commands passed with warnings treated as errors. A Visual Studio x86 build recipe is also included in README.txt, but has not been tested here.

Example launch in an existing test prefix (substitute your local paths):

WINEPREFIX=/path/to/test-prefix \
PROTONPATH=/path/to/GE-Proton11-7-x86_64 \
GAMEID=umu-default STORE=none PROTON_LOG=1 \
umu-run explorer.exe /desktop=CppOverlayProbe,1280x800 'Z:\path\to\LayeredChildProbe.exe'

Expected versus observed

For mode 0, pptDst=NULL should preserve the child's current position and draw inside the parent. Microsoft documents that layered child windows are supported from Windows 8 and that a null destination preserves position: UpdateLayeredWindow. The embedded manifest declares Windows 8/8.1/10 compatibility.

In the self-contained GE test, the top-level window is at (250,200), with client origin (254,223). Every ULW call returns TRUE:

Modes 1–3 are diagnostic experiments, not proposed workarounds. The first mode alone demonstrates the original problem. The pattern suggests a parent/client-to-screen coordinate mismatch, but the responsible Wine/Proton implementation has not been identified. This exact independent test has not yet been run natively on Windows for an A/B comparison.

The probe uses fully opaque ARGB pixels to avoid conflating alpha blending with positioning.

Attachments

• Independent C++ reproducer, manifest/resource, README, prebuilt executable and recorded output (ZIP).
• GE-Proton11-7 log from the C++ probe, collected with PROTON_LOG=1.
• Screenshot of the C++ probe's displaced colored child surfaces.
• Screenshot of Zoom Player's detached modern controls on GE-Proton11-7.

Zoom Player: modern controls detached from the player

C++ reproducer and diagnostic evidence

LayeredChildProbe-cpp.zip

cpp-probe-ge11-proton.log