PCL — native Win32 widgetset (user32/gdi32, zero-dep, best-effort)

• Type: feature (Track B — lib/pcl, built with $(PXX_STABLE)).
• Status: backlog. Child of [[feature-pcl-cross-platform-gui]]. Blocked-by two lanes: [[feature-pcl-seam-seal]] (Track B — a total seam to implement against) and [[feature-port-windows-pe]] (Track A — a PE that boots + the IAT to import user32/gdi32/kernel32). Cannot start until both land.
• Owner: —
• Opened: 2026-07-21, GUI-scope session. (Supersedes the earlier feature-port-windows-gui-pal sketch, which predated the PCL scout — this is a TWidgetSet subclass, not a from-scratch layer.)

What it is

A second TWidgetSet subclass — TWin32WidgetSet — alongside the existing TGtk3WidgetSet (lib/pcl/gtk3widgets.pas:9), implementing the same ~40 virtuals (lib/pcl/uwidgetset.pas:9) against native Win32 instead of GTK. The whole PCL component tree, streaming, and app code sit on top unchanged — that's the point of the seam.

Decision — native Win32, NOT GTK (recorded, do not re-litigate)

• License is not the blocker (GTK is LGPL; dynamic-linking a DLL doesn't copyleft).
• The dependency swarm is — "ship gtk3.dll" is really ~20-25 DLLs + a share/ tree, ~30-40 MB, breaking pxx's single-self-contained-binary identity.
• Native user32/gdi32 = 2 OS-provided DLLs, always present, import-only, zero bundle, zero license. This is the zero-dep doctrine. GTK-on-Windows is refused ([[feature-pcl-widgetset-select]] hard-fails it).

Shape

• Import user32/gdi32/kernel32 exports via the PE IAT (machinery from [[feature-port-windows-pe]]).
• TWin32WidgetSet maps the seam onto Win32: RegisterClassW + CreateWindowExW for widgets, a GetMessage/TranslateMessage/DispatchMessage pump driven by TApplication.Run, a WndProc routing WM_* → PCL's event dispatch (OnClick/OnPaint/…), BeginPaint/GetDC + gdi32 for the TCanvas paint path.
• Single-threaded — consistent with [[feature-port-windows-pe]] deferring threads/sync; the message loop is one thread, no palthread dependency.
• TGLArea may be a sparse/nil capability here (no WGL initially) — allowed per the seam-seal note, not a blocker.

Explicitly NOT guaranteed / NOT gated

No Windows box exists — Wine is the only oracle and is not pixel-faithful. So:

• Correctness, styling, layout, DPI, font metrics, event-timing parity on real Windows are NOT guaranteed and NOT tested. Best-effort only.
• Real-hardware bugs get filed when a Windows box appears, not pre-solved.
• This ticket does not gate the GUI umbrella or the OS umbrella; console+stdio earns "runs on Windows," GUI bolts on.

Acceptance (intentionally minimal)

• A PCL app (TForm + a TButton + an OnClick, built --widgetset=win32 --target=x86_64-windows) opens and responds under Wine (xvfb-wrapped headless smoke via [[feature-t-windows-wine-harness]]).
• Output contains only user32/gdi32/kernel32 imports — no GTK, no bundled DLLs.
• grep -rn 'gtk_' in the win32 widgetset = zero (it's a parallel backend, shares no GTK code).
• Gate: make lib-test stays green on Linux; Windows GUI is Wine-smoke best-effort, NOT a byte-identical or pixel-parity gate.