• Released nuBASIC 1.61

• Added ByRef / ByVal parameter qualifiers for Sub and Function definitions.
  ByRef passes the caller's variable by reference so mutations inside the
  procedure propagate back; ByVal (the default) passes by value. Both
  scalars (Integer, Double, String, …) and user-defined Struct variables
  can be passed ByRef.
• Added support for the Call keyword: Call ProcName(arg1, arg2) is now
  a fully supported alternative to the bare ProcName arg1, arg2 syntax.
• Added the Include / #Include directive: Include "filename.bas" loads
  and executes another source file at the point of the directive, enabling
  multi-file programs and shared library files.
• Added byref, byval, call, and include to the set of reserved keywords
  so they cannot be used as user-defined variable or procedure names.
• Updated built-in help: Help ByRef, Help ByVal, Help Call, and
  Help Include now display documentation for the new language features.
• Added SCREENLOCK, SCREENUNLOCK, and REFRESH instructions for flicker-free
  graphics rendering. SCREENLOCK suspends the automatic per-primitive screen
  refresh so that multiple drawing commands (Line, Rect, FillRect, Ellipse,
  FillEllipse, TextOut, PlotImage, ...) accumulate on an off-screen back buffer.
  SCREENUNLOCK presents the completed frame in a single blit. REFRESH forces an
  immediate blit without altering the lock state (useful before blocking Input$
  calls or game-over dialogs).
• Fixed window repaint flickering on Windows: text and cursor are now composited
  onto the off-screen back buffer before the single BitBlt to the screen,
  eliminating intermediate visible states during WM_PAINT.
• Updated all graphical example programs to use the new screen-lock pattern:
  breakout2.bas, breakout3.bas, pingpong.bas, nutetris.bas, nutetris3d.bas,
  raycast3d.bas, plane.bas, clock.bas, cartoon.bas, minesHunter.bas,
  tictactoe.bas, line.bas, rosetta.bas, calc.bas.
• Updated built-in help (HELP SCREENLOCK, HELP SCREENUNLOCK, HELP REFRESH).
• CLI: after a graphics program ends, the console automatically overlays a
  "Press any key to continue..." prompt on the graphics frame and waits for a
  key before restoring text mode. No explicit keypress code is needed in
  BASIC programs.
• Fixed rosetta.bas, parabola.bas, bitmap.bas: removed manual keypress code
  now handled automatically by the CLI; rosetta.bas timing messages are now
  drawn with TextOut at distinct positions so they no longer overlap.
• IDE: fixed "Evaluate Selection" (F11) freezing after displaying a result or
  error. The timer that dismisses the annotation was incorrectly re-invoking the
  evaluation every three seconds instead of clearing it; errors also caused a
  stale annotation to be shown. Both issues are now resolved.