Block 4200
( user-font-demo.4th -- proves the 4.3.6e override mechanism. )
( Redefines DISPATCH-UPPER, overriding G-A with a marked       )
( alternate (an X through the A) while every other letter      )
( still calls font.4th's existing G-B..G-Z (not redefined).    )
: G-A-ALT ( -- adv )
  100 0 275 700 G-LINE
  275 700 450 0 G-LINE
  190 350 360 350 G-LINE
  100 700 450 0 G-LINE
  550 ;

Block 4201
: DISPATCH-UPPER ( codepoint -- adv )  CASE
  65 OF G-A-ALT ENDOF 66 OF G-B ENDOF 67 OF G-C ENDOF
  68 OF G-D ENDOF 69 OF G-E ENDOF 70 OF G-F ENDOF
  71 OF G-G ENDOF 72 OF G-H ENDOF 73 OF G-I ENDOF
  74 OF G-J ENDOF 75 OF G-K ENDOF 76 OF G-L ENDOF
  77 OF G-M ENDOF 78 OF G-N ENDOF 79 OF G-O ENDOF
  80 OF G-P ENDOF 81 OF G-Q ENDOF 82 OF G-R ENDOF
  83 OF G-S ENDOF 84 OF G-T ENDOF 85 OF G-U ENDOF
  86 OF G-V ENDOF 87 OF G-W ENDOF 88 OF G-X ENDOF
  89 OF G-Y ENDOF 90 OF G-Z ENDOF
  DROP TOFU ENDCASE ;

Block 4202
( DISPATCH-GLYPH/DRAW-GLYPH also redefined here -- found in    )
( 4.3.6c, not just documented in 27.6.5: they were compiled    )
( early too (in font.4th, against font.4th's own DISPATCH-*),  )
( so redefining DISPATCH-UPPER alone would not be picked up.   )
: DISPATCH-GLYPH ( codepoint -- adv )
  DUP  48   58 WITHIN IF DISPATCH-DIGIT        EXIT THEN
  DUP  65   91 WITHIN IF DISPATCH-UPPER        EXIT THEN
  DUP  97  123 WITHIN IF DISPATCH-LOWER        EXIT THEN
  DUP  32  127 WITHIN IF DISPATCH-ASCII-PUNCT  EXIT THEN
  DUP 160  256 WITHIN IF DISPATCH-LATIN1       EXIT THEN
  DUP 8192 8304 WITHIN IF DISPATCH-GENPUNCT    EXIT THEN
  DROP TOFU ;
: DRAW-GLYPH ( codepoint x y size color -- adv )
  GCOLOR ! GSIZE ! GOY ! GOX !
  DISPATCH-GLYPH ;