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F03 — Modal-loop survival ​

On Win32, entering interactive resize/move (WM_ENTERSIZEMOVE) traps the thread in a system modal loop and your message pump stops being yours; on macOS, live-resize runs the run loop in a special mode. An animation that freezes during resize is the visible symptom. This demo proves continuous animation through interactive resize and title-bar drag on every platform, and documents the per-platform technique required.

Requirements ​

  1. Animate a full-window color cycle (~2 Hz) driven by the frame clock from F04's mechanism or a timer; log a frame_callback/tick event per frame with timestamps.
  2. Prove animation continues during (a) interactive border resize and (b) title-bar drag: the inter-frame deltas in the log must stay bounded during the interaction.
  3. Win32 (the headline): defeat the modal loop. Implement at least one technique and document the alternatives considered: SetTimer + WM_TIMER ticks inside the modal loop, rendering on WM_ERASEBKGND/WM_NCPAINT, a render thread that paints independently of the pumping thread, or WM_ENTERSIZEMOVE/WM_EXITSIZEMOVE bracketing with a timer fallback.
  4. macOS: handle live-resize (viewWillStartLiveResize/viewDidEndLiveResize, NSRunLoop common modes for timers) so animation continues while dragging.
  5. Wayland/X11: confirm (and log) that no modal loop exists — interactive resize is just more events; that asymmetry is itself the finding.

Instrumentation ​

tick t=… per animation frame; modal_enter/modal_exit (Win32, macOS live-resize equivalents); the standard resize events from F02.

Findings to record ​

  • Max inter-frame gap during interaction, per platform (from the logs).
  • The chosen Win32 technique, the alternatives, and their trade-offs (cite the relevant Microsoft Learn pages and known framework workarounds).
  • Which thread the modal loop captures, and what that means for a frameworks' loop ownership.

Verification ​

Interactive drag cannot be automated honestly: Wayland/X11 runs under headless compositors prove the no-modal-loop half (Tier A); the Win32/macOS halves are Tier C with a precise manual script. A[wine] runs of the Win32 demo are evidence Wine reproduces the modal loop, not that Windows behaves identically — label accordingly.