# Windows reusable Button fixture

`examples/windows_button/` composes the existing Win32/D3D11 host with the
shared `controls/button` implementation and the app-owned fixture in
`examples/ubuntu_button/fixture/`. The Windows adapter translates native
window/input events and owns only Windows session state; it does not duplicate
Button, accessibility, or activation semantics. This is an experimental
fixture, not a Windows support-tier claim. Native UI Automation remains
unsupported.

The visible 640 × 240 logical-pixel window provides a bounded Stage A demo:
Tab toggles focus, Enter activates on its first key-down, Space activates on
the matching key-up, and a primary-button click activates on an in-bounds
release. The sample uses committed `WM_CHAR` text to toggle `D` enabled state,
`L` loading state, and `R` to reset the fixture-owned activation count and
session. Escape closes the window. These single-letter controls belong to this
example; the shared model remains platform-neutral.

Run the Windows matrix from x64 PowerShell with the pinned MoonBit
`0.10.14+7d59c7ec9` toolchain and Visual Studio x64 C++ tools:

```powershell
pwsh -NoProfile -File scripts/test_windows.ps1 -PortableOnly
pwsh -NoProfile -File scripts/test_windows.ps1
pwsh -NoProfile -File scripts/run_windows_button_e2e.ps1
pwsh -NoProfile -File scripts/run_windows_button_e2e.ps1 -TestCleanupFailure
```

The portable command checks the Win32 package and shared Button model tests.
The full native script builds the Windows C boundary, runs the deterministic
Windows and shared-fixture tests, and launches the visible Button smoke with
opt-in D3D11 staging readback. The smoke requires both `GPUI_NATIVE_E2E=1` and
`GPUI_WINDOWS_READBACK=1`; it fails if it cannot copy and validate the
completed frame. The separate E2E runner sends real keyboard and mouse input
only after checking x64 `INPUT` layout, owned HWND identity, foreground, and the
active `Default` input desktop. Its records are saved under
`_build/windows-button/e2e/`.

## Current evidence and limits

On 2026-10-10 the native smoke completed one D3D11 frame at scale 1.0 with a
640 × 240 readback. It measured background `[24,28,36,255]`, the enabled Button
fill `[42,71,101,255]`, 183 bright label pixels, and 279 status-text pixels.
The observed host was Windows 11 Pro build 26200, x64, MSVC 19.44.35214.0,
MoonBit compiler `0.10.14+7d59c7ec9`, a 3440 × 1440 desktop, and an NVIDIA
GeForce RTX 2060 SUPER (driver 32.0.15.6614). The fixture uses Segoe UI; the
observed `segoeui.ttf` SHA-256 was
`8134dbcd09e7b123c9a7f229d49cffbcb01352cc72ea5e1076b65d0dca9f73cd`.
The backend's hardware-versus-WARP choice was not recorded, so this is a
completed-frame pixel check on that host, not a GPU-driver matrix result.

The visible SendInput run recorded `BLOCKED`: this session could not open the
active input desktop (`OpenInputDesktop`, Win32 error 5) and had no foreground
HWND. Physical keyboard/pointer interaction and GUI close/reopen are therefore
`UNRUN`; the runner does not substitute posted messages or model tests for
physical input. `scripts/run_windows_button_e2e.ps1` preserves that status in
`result.json` and can be rerun from an interactive session with access to the
Default input desktop. `-TestCleanupFailure` runs a deterministic child-process
self-test that exits nonzero and writes stderr; it checks that cleanup records
the exit code and error text, without launching the Button window or attempting
input. The six Windows session adapter tests and 16 shared
Button fixture tests cover model-level repeat suppression, activation counts,
enabled/loading/reset transitions, semantic snapshot freshness, close/blur,
resize cancellation and stale releases. They do not qualify physical input or
all state-specific native pixels.

The D3D11 sample validates a few pixels from the completed frame; it does not
qualify clipping at arbitrary dimensions, high-DPI transitions, monitor
moves, all fonts, UI Automation, Japanese IME, broad Windows compatibility, or
production support. See [issue 0025](../issues/open/0025-windows-button-integration.md)
for the remaining acceptance gates.