Panel number fields (num_field: X, Y, W, H, corner radius, stroke
weight, font size...) only parsed their text on Enter or focus loss,
so the arrow keys did nothing. With the field focused, Up/Down now
step the value by one of the field's unit (Shift: ten, Ctrl/Cmd: a
tenth), from the value shown, and apply it at once, as in the
reference app.
The field's focus is read from egui's memory, as its highlight and its
typing do: Response::has_focus also needs the window to report
keyboard focus, which the running app's window doesn't always do.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>