User blog comment:Lumage/Lumage's totally not crap GRP editor./@comment-75.143.146.100-20150427032346

Even I can do better than this. Look, short and simple:

PNLTYPE "OFF"

COL=0

@LOOP

CLS

GPAGE 0

GFILL 0,0,40,40

GPAGE 1

GFILL TCHX,TCHY,TCHX,TCHY,COL

IF BTRIG==1024 THEN GCLS

IF BTRIG==1 THEN COL=COL+1

IF BTRIG==2 THEN CON=COL-1

IF BUTTON==8 THEN COL=COL+1

IF BUTTON==4 THEN COL=COL-1

IF COL<0 THEN COL=0

IF COL>255 THEN COL=255

WAIT 1

GOTO@LOOP

Wasn't that easy???