Windows Ink (pen tablet input) doesn't generate SDL_EVENT_MOUSE_MOTION events in fullscreen

[Susko3]

• Originally reported in SDL3: Tablet hovering impossible without turning on "Tablet" option in input settings. ppy/osu#30641

Moving the pen over the tablet (without pressing down) generates SDL_EVENT_MOUSE_MOTION events when in windowed. But setting the window to fullscreen, the events suddenly stop arriving.

If the pen is pressed down, SDL_EVENT_FINGER_MOTION events (with touch name = "pen") arrive as expected, in windowed and fullscreen.

[DennyLindberg]

Related issue
#11479

[icculus]

I haven't tested this since Windows Ink support landed; does this plus #11869 settle this issue out?