SDL's Steam Deck mapping delivers the pad clicks as gamepad BUTTONS with no
surface identity: the generic `touchpad` button is the LEFT pad's click and
`misc2` the RIGHT's (SDL_gamepad_db.h `touchpad:b17,misc2:b16`). The client
forwarded `touchpad` as wire BTN_TOUCHPAD — which the host maps to the RIGHT
pad click (DualSense convention) — and dropped `misc2` entirely: a left-pad
click registered on the right pad, a right-pad click nowhere, and the
mis-routed state could stick.
Clicks from a multi-touchpad pad now ride the rich plane as TouchpadEx with
their surface, reusing the surface's live contact point (click buttons carry
no position). forward_touch carries the held click through motion frames so a
touch update can't clear a click mid-press, and the flush lifts held clicks on
detach/pad-switch. A DualSense's single touchpad button stays on the button
plane unchanged.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
db63647337