UScreen 1.2.6 — USB second monitor for Linux with S Pen support

The first of the regular Saturday releases — from now on fixes collect
during the week and go out together on Saturday evening (US Eastern time),
unless people cannot use UScreen without one.

It picks an encoder that works

A fresh config said h264_nvenc, and nothing ever checked whether that could
work. On a laptop without NVIDIA, ffmpeg died on every start and the tablet
sat on a spinner forever; uscreen doctor even called the encoder
"available", because ffmpeg -encoders lists what ffmpeg was built with
(#15).

The daemon now encodes one small test frame with the configured encoder and,
if that fails, takes the first of NVENC → VAAPI → libx264 that works, says so
and saves the choice. doctor checks the same way. If you are on AMD or
Intel graphics and UScreen never showed a picture, this is the fix.

pointer_handoff

After the pen lifts, UScreen parks an ordinary mouse cursor where it was. That
also means the shared desktop cursor is now on the tablet, and carrying on
with the mouse means dragging it back first. pointer_handoff = false — a
checkbox in the GUI, Leave the mouse cursor where the pen was lifted —
creates no pointer device at all: pen and touch drive the tablet's screen, the
mouse stays where it was (#18).
Default unchanged. That report also found the parked cursor landing left of
the pen on mixed-scale layouts; that is not fixed yet, and turning the handoff
off avoids it.

Also

• GUI: the config path no longer draws on top of the status message
  (#16).
• Two more systems in the compatibility list: Q4OS on a two-core AMD 3020e,
  and Arch on Intel Raptor Lake.

Update both halves together. Files: .deb, .rpm, PKGBUILD archive,
portable tarball, uscreen.apk, SHA256SUMS.