On pen-down the OS drew the "Windows Ink" tap ripple / press-and-hold ring
under the nib — ugly and laggy-looking while writing. Set the tablet input
service's MicrosoftTabletPenServiceProperty on both the top-level window and
the Flutter child (where WM_POINTER lands) with the disable flags
(PENTAPFEEDBACK, PRESSANDHOLD, PENBARRELFEEDBACK, TOUCHUIFORCEON/OFF, FLICKS)
so the pen draws instantly with no OS animation.
Native-only change (windows/runner/flutter_window.cpp); built by CI.
Akiba So
8908f42f76